A pitching trade

The major league season resumes today, but on Thursday we got a notable pitching deal, which kinda sorta is the first volley of the midseason trading period. (That discounts the James Shields trade last month.)

San Diego shipped Drew Pomeranz, who was named to the NL All Star team, to Boston for prize prospect Anderson Espinoza, an 18-year-old pitching in low A ball. Baseball America rated Espinoza the 19th prospect in baseball during the offseason. That's a pretty solid pickup for a lefty who has already set a career high for major league innings.

That one is going to hurt Boston if Pomeranz turns back into a pumpkin. https://t.co/BHupRuLKLe

— John Manuel (@johnmanuelba) July 14, 2016

Yeah.

Pomeranz is reputed to have turned his career around by adding an effective cutter to his arsenal, giving him a third pitch. It's quite possible that he is indeed now a better pitcher than he was a year ago; it's possible for a pitcher to add a pitch, discard a pitch, change his arm angle slightly, change his stride -- do one thing differently -- and have that make a huge difference.

But I am habitually suspicious of pitchers who thrive in San Diego and Petco Park and then move elsewhere. Environment matters, and the difference for a pitcher between Petco and Fenway is huge.

Beyond the wisdom of this deal: This trade may affect the asking price for other starters. There are reasons to value Pomeranz over, say, Ervin Santana -- youth, contract, upside -- but there is also reason to believe that Santana is the more reliable starter. Espinoza may well be the top prospect dealt this month, but that he moved at all may prompt the Twins to raise their sights on Santana in the next two weeks.