Watson played a lot of whiffle ball last season, I thought he was still doing it in preseason, but he has been much improved this year, he doesn't have that same dominance Graham has, but he is sticking to his blocks and rarely misses - major improvement. Pass blocking is still a weakness, but I'm confident he will get better.
I also thought Thomas was "just" a receiver, but he showed up in the preseason as a blocker and has steadily improved - note that Watson is getting many more passes, Thomas has had a couple long ones and that sweet grab for a 1st down over the middle against Miami, but he is kept in to block more often. It could be that Tommy just prefers to throw to Watson, but if Thomas couldn't block, they wouldn't be so quick to keep him in.