AFL ACADEMY coach Brenton Sanderson believes young Western Bulldogs key defender Kieran Collins has the attributes to make an immediate impact at senior level.

The Bulldogs were pleasantly surprised when the Under 18 All Australian was still available at their second selection (pick 26) and Sanderson believes his former protégé was one of the biggest bargains of 2015 draft.

Collins' arrival at Whitten Oval couldn't have come at a better time with the Dogs' key defensive stocks needing replenishing after Michael Talia's departure and veteran Dale Morris in the twilight of his career.

"Expect him to come in, play straight away and fit into the Western Bulldogs side no trouble at all," Sanderson told AFL.com.au.

"I rate him really highly; he was one of the big improvers in the national academy program in 2015.

"He started off the year really well and he just kept on getting better and better, so he'll adjust really quickly to the AFL system."

While not the tallest key defender at 194cm, the 18-year-old is already tips the scales at an imposing 95kg and Sanderson says the Dandenong Stingrays' product will need that bulk to contain the AFL's monster forwards.

"He'll probably spend most of his career playing on 198cm plus key forwards, so he's going to have to learn how to use his body and read the play," Sanderson said.

"I guess an inspiration for him would be players like Josh Gibson (189cm) from Hawthorn and North Melbourne's Scott Thompson (193cm) who certainly play that role really well."

What he lacks in height, Collins makes up for it with flexibility and an insatiable appetite for the contest, two attributes Bulldogs coach Luke Beveridge demands from his players. 

"It didn't matter who he played on, he had the ability to beat guys who where taller and stronger and he had great success against players who were smaller and more agile," Sanderson said.

"He gained great confidence from beating a few players who went early in the draft (Josh Schache and Sam Weideman), but the thing I like about Kieran is he picks up stuff really quickly and learns on the job.

"And he fights until the death, there's no doubt about that."

While many recruiters pigeonholed him as a dour stopper early in 2015, Collins defied those beliefs by adding some attacking traits to game.

Finishing fourth for intercept marks at the Under-18 Championships and claiming the clean hands test at the draft combine were evidence of his vast improvement.

"He's an intercept marker and he got better and better at getting his hands on the footy and providing some offensive drive," Sanderson said

"He really improved his kicking, too, so it's testament to his rise, as a lot of recruiters wouldn't have seen him as a top 30 pick at the start of the season.

"He's got fantastic character and he's certainly made of the right stuff."