PADDY McCartin's foot injury isn't stress related, and there is no reason it should cause the big Saint further complications, backline coach Danny Frawley says. 

McCartin, 21, hurt his right foot last Monday to continue a luckless run, although he is expected to be back in full training by the new year. 

The forward's 2017 season was ended in June by his sixth concussion in the past three years and McCartin has been restricted to 22 games since he was drafted with the first overall selection in 2014. 

Frawley explained how the injury occurred to SEN on Thursday morning.

"It happened through a little handball drill. It wasn't stress related. Someone's actually pushed him off balance and stood on his foot and he's had a mid-foot sprain, so it was through a collision-type scenario," Frawley said. 

"He's off his feet for a couple of weeks. He's still got the best hands in the game. Not ideal but it is what it is and he'll be back training fully after Christmas." 

Expectations are high for McCartin, especially with legendary Saint Nick Riewoldt having retired. However, Frawley said critics should wait before casting judgement on Riewoldt's potential successor. 

"You've got to be patient with a key position player. Their best football is from 24 to 30, I've got no doubt, because they're playing against guys like my nephew (Hawthorn defender James Frawley), who are 28, and are just athletic beasts," Frawley said.

"It takes a lot longer for a key position player to actually get there and we've just got to be patient. 

"This is a good test for Paddy. He will have a different program. Head down, bum up. it's as simple as that."