In the article, he said he feels more comfortable with the change, and the sinker is brand new, never used in a game. It's almost impossible to be an MLB starter with a two-pitch arsenal, so that is a great development.
Wicks worked on mechanical processes and adjusted his grip to achieve greater sink. But his real problem is the same as Assad, they are bad-bodied pitchers who lack conditioning to make it through a full season. If he can't stay healthy and in the rotation, he's going to be a relief pitcher. This is his last chance at starting, and he should be a trade candidate this season.
I don't know the rules of MLB, but I don't understand why the Cubs don't invest in offseason programs for these guys. And by that I mean don't give them a to-do list. Get them a team of nutritionists and biomechanists, and keep them in Arizona for at least part of the offseason to monitor and manage them.
Same with Mo. There is no reason he should come to ST grossly overweight.