One challenge is Little never really threw a 4 seamer in game, so we don't really even have a base to compare a velo gain against.
4 seamers are "typically" 1-2 MPH harder than a sinker. If Little threw a 4 seamer, it might have already been 95+ last year. It's averaging 96.7 this spring, so that wouldn't be an usual velo gain IMO. That said - hitting 98.4 MPH certain grabs your attention!
I always found his pitch mix a little odd. Typically guys with hammer curveballs utilize a 4 seam fastball and then you have sinker/slider guys (although this might be a bit outdated now). I wonder if they want Little throwing at 4 seamer at the top of the zone so he can tunnel that curve better - start it out at the belt so he can land it for more called strikes. That would make a lot of sense from a guy who clearly needs to throw more strikes.
When you're trying to tunnel a sinker and a curve that starts at the knees and dives out of the zone - it's easy to see why he walked to many.
I'm sure sliderguy can educate us all in what Little should be doing.