Wisler's one of the guys I have a hard time getting a read on. He's got a full arsenal of pitches but all of them are pretty average. His slider is probably his best pitch but it's still not a dominant out pitch. The lack of any elite offering has no doubt contributed to his struggles in getting K's. Based on what he's done in the high minors and what he did in Atlanta last year, it's tempting to write him off as nothing more than a back end of the rotation starter who has an outside shot at being a middle of the rotation guy.
However, you look at some individual performances and it's kind of confusing. In 7 of his 19 starts, he struck out a batter or less for every 2 IP. But then again in 6 of his 19 starts he struck out a batter or more an inning. So 13 of 19 starts he was either getting lots of Ks or hardly any. It's confusing.
I think a lot depends on if he can improve any of his pitches. If he can raise his fastball and slider both to plus pitch level (still possible), he has the rest of the arsenal, control, and "pitchability" to excel. However, if he struggles to have a consistent out pitch, he'll languish as a fringy starter.
Personally, I'm expecting him to eat some innings this year with an ERA of about 4.20. Number 4 starter kind of stuff.