Miguel Castro to sign for Diamondbacks; also add C Ali Sánchez; lose P Sean Poppen

Robert Murray of FanSided Tweets that the Arizona Diamondbacks are in agreement with right-handed reliever Miguel Castro. He reports that the contract is for one year at $3.5 million, but Jon Heyman says this “includes incentives and option”. The latter is presumably for the 2024 season, but I have not yet heard whether it’s a team, player or mutual option. There’s no denying Castro’s potential, and he certainly provides a power arm. His fastball last year out of the Yankees bullpen averaged 97.9 mph. That instantly makes him the hardest thrower on the D-backs roster, more than a mile per hour above the 2021 leader, Luis Frias at 96.8 mph.

However, there are two major issues which have stopped the 27-year-old Castro (he turns 28 next month) from achieving greater heights: health and control. He threw only 29 innings for New York last year, with a shoulder strain keeping him out of action for much of the year. That’s not a phrase you like to hear with any pitcher, in particular those who throw hard. There’s also a career walk rate of 12.3%, significantly above the MLB average of 8.4%. His career strikeout rate is below average (20.5% vs. 22.1%), but has spiked up sharply over the last three seasons, to 26.6%. This may be linked to an uptick on Castro’s velocity around the same period.

All told, Castro has a 4.12 ERA (106 ERA+) for his career, though his FIP of 4.73 is quite a bit higher. Again though, the number over the past three years have been better: 3.70 ERA, 111 ERA+ and 4.15 FIP. We’ll see if Brett Strohm can work his magic on Castro. As well as cutting down on the walks, it’d be nice to see the pitcher improve his spin rate, which was in the bottom quarter of pitchers. Combine that with the top tier velocity, and he could potentially become an unstoppable force at the back of the Diamondbacks bullpen: at least, we can hope so. Otherwise, he may end up becoming just another in a long line of future Arizona ex-closers.

Update. The team’s official announcement of the Castro signing also included a couple of other roster moves:

Ali Sánchez has a cup of coffee experience in the majors, with just seven games between the Mets and Cardinals. The D-backs will be his fourth different organization just this year (paging Makakilo!), without reaching the majors. He began in AAA for the Cardinals, but was selected off waivers by the Tigers, then the Pirates and now the D-backs. The team does have a need for a backup catcher: whether Sánchez will represent that, or simply additional depth at the position, will have to be seen. He is only 25 years old at this point, so is still relatively young.

Meanwhile, the D-backs lose the smartest guy in the room, “Professor” Sean Poppen and his double major (with honors) from Harvard in Chemistry/Physics, and Engineering Sciences. Still, easy come, easy go, as Poppen was selected by the D-backs off waivers from the Rays in August 2021. He had a 4.50 ERA (92 ERA+) over 46 appearances and 49 innings for Arizona, with a K:BB of 43:19. He was pretty much at replacement level as a pitcher - unlike his performance as a student.