I don't think Thomas will have as much trouble with the midline as many here think. It isn't a power play; if you look at successful examples posted here, if the read is right, the player getting the ball is seldom hit solidly.
Also, if you look at some films of Keenan Reynolds running the midline, you will see that he is quite good at hiding behind blocks and then using his speed to get through to open territory. Last year Reynolds was the same size as Thomas this year. If JT learns how to read the play I don't think he'll have any big problems running it.
Oh, and on the OL: the main reason that the blocking looks better is that everybody is scared of Dwyer. That means they hold back on their initial move. Last year Vad was running almost all tosses and double options. That made things easier for the Ds. Also, I expect that BB will be a bigger threat this year. Not up to Dwyer, of course, but big enough to get that sudden hesitation that's all the O needs. We'll know if I'm right soon enough.