Seems like he has not pitched well at all lately, wondering if something is wrong?

If you look at last year stats it seems he falters in August but rebounds in September.

Not sure I'd be worried just yet. He's had a fantastic season... might be just hitting a dead arm period... Honestly, I wouldn't mind a 10 day DL with him to get a look at Gonsavles.

I wouldn't say 'worried' either.  I think he is what he is at this point.  Which is to say that he's put together a solid year so far at age 24.  His 2018 has been a solid improvement on his 2017 campaign, and there's no reason to think he can't do that again 2018 to 2019.

 

It helps to simply acknowledge that he is not really an 'ace' or a 'stopper' quite yet.  His numbers against teams that are 500 or better...those that tend to have better/more experienced lineups...are not very impressive (even when you include his notable 'good' performances against Boston).  He's going to have these games.  He's 24, and has a few things to figure out still.  

Pitchers go through stretches of whatever.

 

I notice that the days he struggles are the days he struggles with his nasty breaking pitch.

No