Honestly I am not so sure about Jonas V. He is only averaging 3.7 minutes in the 4th quarter. He has played 13 games with zero minutes in the 4th quarter. I found someone say this in an NBA forum
"He's not very good defensively, and doesn't give as much effort as Amir and Patterson, imo. Stats also indicate that the Raptors are better on both ends of the floor when Amir and Patterson are out there together. Valanciunas doesn't need to be out there in the fourth quarter to improve his game since he plays decent minutes, and the Raptors have a better shot of winning if they go with their superior lineup. Raps fans have an oddly high opinion of Val. He's a slow post-up player with questionable footwork and below average defense. He might get there eventually, but there is no justifiable reason for Casey to play him in the fourth right now."
and then someone who is a raptors fan says this
"I completely agree with you. I not a huge fan of Casey, but I agree with him on not playing JV much in the 4th. I have no idea what other raptor fans see in him. Everybody ignores how bad he on defense, particularly on pick and rolls and his help defense. Whenever other teams go small, raptor fans are up in arms when Casey goes small as well, instead of letting JV take advantage of the match-up, ignoring the fact that he is not good enough on offense to overcome his lack of ability to guard smaller, more mobile big men."