Actually there is always a chance of an Injury, which would obviously at least get him a chance at a run.
tbf even with an injury to Arheiner I would still play Schaw in the Centres We needs his tackling ability there.
What about durability or whatever it is. Because that will also effect your Injury rate (although I think everyones, durability and fitness are the same) still there is always a chance, no matter how remote.
Bots doesn't want to look bad because the opposition breaks through the defensive line on his side because he can't tackle.
Put it this way, i like the idea of Schaw being on your side TBH your defense stats aren't to bad considering your 93-7 split.