Midfield wunderkind Brad Crouch was struck down in early 2014 with a broken leg, which restricted him to 11 games in his second season. Crouch still averaged 25 disposals a game, and on the back of a what's shaping as a stellar pre-season, he appears set to really break through next year. The 20-year-old's intensity at training is amongst the highest at the club and his performance during conditioning sessions points to real aerobic development. An Achilles issue robbed him of a pre-season heading into 2014 so the club is excited as to what he'll produce with a summer of training behind him.  Harry Thring
Third-year key forward Michael Close knows there's a big opportunity next season and he's doing everything he can to grab it. With Jonathan Brown now in retirement, Close wants to be the go-to man in the Lions' forward line. He has consistently finished top-three in the club's 2km time trials – not bad for a man standing 196cm – and has also added 2-3kg to his frame. Close is noticeably bigger in the upper body and is constantly getting closer to the body needed to play as a power forward in the AFL. - Michael Whiting
With Jarrad Waite departing for North Melbourne, Carlton needs Lachie Henderson and Levi Casboult to continue their improvement as key forwards, and Casboult has given every indication he is ready to assume more responsibility in his fifth season with the club. Carlton's director of development and coaching Rob Wiley said a number of Blues have been training superbly but that he had been most taken with the 23-year-old man-mountain. "Levi's athletic ability is just outstanding. I think having a full year of AFL for the first time (this year) taught him a lot of lessons and he's come back very fit and strong. He's a quiet young man but he's also coming out of his shell somewhat." As for the former rookie's major deficiency, his kicking for goal, Wiley said: "Admittedly it's only training but he's kicking the ball well. He's working on his technique and he's been having lots of shots on goal. We saw some improvement this year when he altered a couple of little things and he's gained confidence from that." - Ben Collins
Steele Sidebottom may be the undisputed 2km time trial king at Collingwood, but there's one firing youngster who is quickly closing the gap. Nathan Freeman has been lighting up the track this pre-season and is firming for an early season debut as a result. Freeman was the standout performer during the Magpies' camp, specifically designed for the club's first-to-fourth-year players, in Falls Creek in December. He won the club's 'young players' time trial and fell just short of Sidebottom when the full squad was back into training. The 19-year-old has an elite endurance/speed combination, so you should expect to see him receive plenty of senior opportunities next year. - Ben Guthrie

The Bombers will be hoping some of their improvement comes from a group of players who have been at the club a handful of years, and the early signs are good. Elliott Kavanagh and Jackson Merrett have been among the early standouts to impress the club during pre-season with their running and ball work, as both head into the fourth season of their AFL careers. Merrett had a strong start to last season before his form dipped while 2015 is an important season for Kavanagh, who requested a trade during last year's exchange period before staying with the Bombers. He will be looking to break into the club's first-choice midfield having played seven games in his first three seasons.  Callum Twomey 

Essendon players in action during the time trial at Princes Park. Picture: AFL Media
He has always been a strong performer in the pre-season but Matt de Boer has really stepped it up a gear this summer. He pushed the club's best runner Tendai Mzungu in the 3km time trial, on the back of the pair training together during the off-season. Both endured gruelling running sessions together away from the club and de Boer has reaped the rewards so far. He signed a one-year deal after an indifferent season last year due to a knee injury and some form issues but he is setting himself for a huge 2015 with an exceptional pre-season so far. Young midfielder Tom Sheridan has also impressed with his performances so far. Alex Malcolm
Pre-season is Mark Blicavs' domain, so there's little surprise he is leading all comers in the running stakes. But ask the Geelong players and it's Cameron Guthrie's improvement that has made the biggest impression at Kardinia Park this pre-season. The fifth-year midfielder has stepped up into the top running group at the club, as he continues to progress from his previous defensive role to that of a bona fide midfielder. Josh Caddy has impressed in the football specific drills and is looking extremely fit, while gun defender Harry Taylor has dropped four kilograms after hiring a running coach in the off-season. – Nat Edwards
Prodigiously talented West Australian Jack Martin has worked tirelessly to add size to his wiry frame. He played last season at a lean 74kg, but has put on 5kg of muscle, much of which is through his legs. The explosive midfielder/half-forward has also managed to improve his already solid endurance, running a personal best (6.38) in the final 2km time trial before the Christmas break. A special mention should go to small defender Sean Lemmens, who in 12 months since joining the club, has gone from one of the slowest over 2km to recently breaking seven minutes for the first time. - Michael Whiting
With Tom Boyd now a Bulldog and Jonathan Patton on the comeback trail from a knee reconstruction, many are asking who will be the next big forward to fill the breach alongside Jeremy Cameron next season? The answer could be Adam Tomlinson. As Giants coach Leon Cameron recently told, Tomlinson has largely been forgotten outside of Spotless Stadium. But the 21-year-old has one of the "biggest motors for a 196cm player" Cameron has ever seen, has 45 games and 15 goals under his belt and is a former No.10 draft pick. Tomlinson also won the Giants' 3km time trial for first-to-fourth year players on day one of pre-season and seems ready to explode in 2015. - Travis King
GWS says Adam Tomlinson, a '196cm running machine,' is ready to step up. Picture: AFL Media  
The Hawks are producing a daily video recap of their training camp on the Sunshine Coast and there is vision of Billy Hartung gliding through a sprinting session while the other players appear to be labouring in the sweltering tropical conditions. Hartung is an elite runner and his second pre-season at the Hawks could yield spectacular results, the same as Bradley Hill this time two years ago. Sam Mitchell told the club's website that Hartung’s form in pre-season to date has been "absolutely outstanding”. Mitchell is a hard marker, so this is high-praise indeed.  Ashley Browne
Ask Melbourne officials about Jesse Hogan and they go quiet. It's as if you're asking a major betting stable about a horse before its first start. Melbourne has every reason to be both cautious and excited about the 19-year-old. In two 1km trials held late in December, Hogan ran in the second fastest group of eight players, matching strides then defeating fellow key forward Chris Dawes - a player with a well-earned reputation as a superb track worker. It's not just Hogan's endurance but his delivery inside 50 and the target he provides when charging out of the square that has impressed those observing his progress. Given the back problem that ruined his 2014 season, he is being monitored closely to ensure he develops good training habits and he will be eased back into full match practice. But he has made the best start possible to pre-season. His teammate Jack Viney – who was chosen as a father-son selection in the same draft as Hogan – is also eating up the work. He had two excellent years off limited pre-seasons but his pre-Christmas period has been exciting for observers. - Peter Ryan
He's yet to play a game but there's huge excitement building around Jesse Hogan. Picture: AFL Media
Former Dog Shaun Higgins has impressed all at North with the flying start he has made to his first pre-season at Arden Street. With the Bulldogs finishing their 2014 season three weeks earlier than North, Higgins took full advantage of his longer off-season break, dedicating himself to a fitness program that had him in excellent condition when he reported for day one of pre-season training. The utility has not missed a beat since. He has performed solidly in all of North's running sessions, while his class has shone out in match-practice drills. - Nick Bowen 
After winning a second consecutive Gavin Wanganeen Medal in 2014 as the Power's best under-21 player, Ollie Wines is preparing to become one of the game's best contested midfielders in 2015. The ox-like 20-year-old was one of the stars of Port's training camp in Dubai, even wrestling with midfield manager Michael Voss. So much of Wines' power originates in his thighs and while he wouldn't want to jepardise that strength, he has slimmed down slightly which has boosted his speed and will allow him to cover more ground next year. As the Power's premiership window opens, the man they call 'Quadzilla' is positioning himself to play a huge role in the campaign.  Harry Thring
Ivan Maric looks set for a big summer campaign after returning from the break fully fit, having avoided surgery of any kind. Reece Conca is another the Tigers are hoping benefits from a full program after battling injury-affected summers every year since he was drafted. Ty Vickery was one who started joining in sessions with the younger players ahead of schedule in a bid to increase his chances of senior opportunities in 2015, while Brandon Ellis (as usual) stood out in time trials early on. Brett Deledio is motivated to put his Achilles problem from this season behind him and capitalise on the half-forward role he ventured into this year.  Jennifer Phelan
The Saints exposed their players to a tough hill running regime on their training camp in New Zealand in early December, and it was Seb Ross, Jack Newnes, Mav Weller and David Armitage who stood out. Jarryn Geary showed his injury-hit 2014 didn't hurt his endurance when he took out the first time trial of the summer. Defender Dylan Roberton is another who is impressing, with the former Fremantle backman adding size to his frame in a bid to fill more of a key position role next season after an ankle injury last pre-season affected the way his year panned out.  Jennifer Phelan
Jack Newnes has been a dominant performer on the track for the Saints this summer. Picture: AFL Media
This time last year, Tom Mitchell was barely running as he worked through his recovery from an ankle injury, so it has been encouraging for the young midfielder to make a bright start this summer. Mitchell completed an off-season running program for the first time since joining the Swans in the 2011 NAB AFL Draft, and it has reaped significant benefits. He started pre-season on day one for the first time and was a standout in both 3km time trials. Putting on size is not a concern for the contested ball specialist, so improving his fitness can be a priority. A breakout year looms with a clean bill of health.  Nathan Schmook
This won't surprise any Eagles fans as Chris Masten is well known for his performances during the pre-season. He ran 6min flat in the 2km time trial although his club record of 5min 58sec was broken this summer by new draftee Damien Cavka. But what will please Eagles fans is Masten's ball work over the summer. He has worked exceptionally hard on his kicking over the past few years and the Eagles' coaching staff are delighted with his output during the pre-season. The Eagles work tirelessly on their ball movement throughout pre-season sessions and Masten's kicking has been a feature. Another who continues to shine is Brownlow medallist Matt Priddis. After one gruelling match simulation session, Priddis stunned his teammates by heading back out on the ground for some extra skills work after the session was completed. Alex Malcolm
Marcus Bontempelli quickly became a household name in his debut season, playing 16 games and finishing runner-up to young Lion Lewis Taylor by just one vote in the NAB AFL Rising Star Award. Not one to rest on his laurels, the 19-year-old has returned to the Whitten Oval in November noticeably bigger, having added an extra 7kg to his 193cm frame. The tall midfielder kicked off his second pre-season with a top-three finish in the 2km time trial behind Lachie Hunter and Mitch Wallis. He also was one of the best-performed players in the handball and kick challenge in the first week back at training. Bontempelli has definitely caught the eye of many this pre-season and the talented teenager looks set for bigger and better performances in 2015. - Nat Edwards