People have been acting like Wheeler's a disaster, but a 4.15 ERA for a kid's first 4+ games isn't exactly a red flag. His stuff is good enough that he can work on his command in MLB. It's not like the Mets are playing for a playoff spot this year.
From what I've heard, before the Giants changed Wheeler's mechanics, the CB was his second best pitch. After the change, ZWs cut slider was the second best pitch. He's gone back to his original mechanics and it's taken time to get back his CB. But, when he's on, the CB is the second best pitch.
"Friend Romans & Country Men Lend Me an Ear" Hannibal Lecture in Florence. Recipe from the Grand Dictionaire de Cuisine, (1873), Alexandre Dumas.