Prior to today's start, De La Rosa has surrendered a home run on 19% of all flyballs he's surrendered. and 1.5 HR/9 (home runs per 9 innings). That's a pretty ridiculous amount, especially when you consider that he's had a decent strikeout rate (8.18 K/9) and a decent walk rate (2.28 BB/9). With peripherals like that, ERA estimator xFIP suggests that his ERA should be about 3.30.
So is Rubby simply really unlucky? James Shields has had a similar issue with home runs this season, with a 17.9% HR/FB.. Shields had a similar HR issue in 2010 when he had a 1.50 HR/9 and 13.8% HR/FB. His xFIP? 3.55. His peripherals were very similar to De La Rosa's, and they've stayed the same, with much more success, ever since. Shields is known to be a pretty good pitcher, and De La Rosa seems to demonstrate similar ability.
C.C. Sabathia has had pretty good strikeout and walk rates, suffering from HR issues as well in 2015. a 1.7 HR/9 rate is simply absurd for a pitcher of his caliber. Yes Sabathia isn't what he once was, but he's simply just giving up more home runs than he should be. His peripherals throughout his career have been comparable to De La Rosa's this season. He's a
If De La Rosa really can become anything like James Shields or C.C. Sabathia, that would obviously be a best case scenario. Top prospect Archie Bradley's struggled and ace Patrick Corbin still working his way back to regaining his prior pre-Tommy John surgery form. If De La Rosa turns things around in the second half to join surprising success story Robbie Ray as solid cogs in the rotation, the Diamondbacks may have at the very least a mid-rotation starter in the making. He still has ace upside and Arizona is right to stick with him.