With the rosters expanding on September 1st, the Diamondbacks have an opportunity to add some depth to their playable roster. Players on the 40-man roster like Anthony Banda, Jimmie Sherfy, Jack Reinheimer, and Jeremy Hazelbaker will be available to add depth to their respective spot. The team does have a free roster spot given the news earlier this month with Rubby De La Rosa staring down another possible Tommy John surgery after successfully coming back from a torn UCL for a short time.
LHP Jared Miller
Miller is the only one on this list who has a real chance to impact the club over the next 7 seasons if we’re counting 2017. After shining in the Fall League last October, he picked up right where he left off after getting assigned to AA Jackson. A rough month of April somewhat skewed his overall numbers, but finished there with a 3.89 ERA/2.73 FIP. The strikeout rate stuck at a solid 29.7%, although the walk rate was a bit high at 10.5%, just missing the K-BB% of 20% I’m looking for in pitching prospects as either top of the rotation or back-end of the bullpen type guys. If you take away the month of April, Miller pitched to a 1.73 ERA/2.29 FIP with a K-BB% of 25.2% in AA.
The strong May and June resulted in a promotion in AAA where he’s gotten even better. After an uncharacteristically high line drive rate of 23% resulted in a .313 BABIP after being .281 and .283 last year in Visalia and Mobile, the numbers autocorrected when he reached Reno. His strikeout and walk rates have improved to 34.8% and 8.0% in just under 30 innings. The K-BB% jump to 26.8% is a very positive sign in his development and suggests that he’s ready for the big leagues. After proving it in the Fall League, AA, and AAA, there’s not much left for him to prove in the minors.
Miller stands at 6’7” 245 and uses his size well to generate a downhill plane on his two pitches making them tough to lift in the air. His ground ball rates have hovered near 50% for most of his career, so not only does he miss bats he also doesn’t give up air contact. Having those two skills projects well for a long term future as a big part of the Dbacks bullpen for many years. His main pitches are a 90-93 MPH heater and a very devastating cut-fastball that serves as his primary out pitch. He’s also featured a curve and a change back in his starter days, but those pitches aren’t critical to his success in the bullpen. This is probably an unfair comparison for Jared Miller, but there are a lot of similarities in his game to another 6’7” left-handed relief ace named Miller.
1B Christian Walker
Walker had a near historic season for the Aces, but ultimately has zero shot of making an impact for the Dbacks because of some other right-handed slugging 1B named Paul Goldschmidt. While Goldy is having an MVP caliber season at the MLB level, Walker is doing the same for the Pacific Coast League. Walker’s 32 home runs leads all minor league players, but his overall numbers are pretty solid. He’s posting a .297 ISO with a solid strikeout rate of 17% and a good enough walk rate at 10.2%. With the Diamondbacks on a playoff push, there won’t be very many opportunities for Walker to get playing time, so he’d have to play in a pinch hitter role where he comes off the bench against LHP. Walker doesn’t have major platoon splits (.997 OPS vs. RHP, .976 vs. LHP) from his Reno numbers, but having a right-handed bat on the bench is something the Dbacks could use in the final month.
OF Oswaldo Arcia
Arcia was invited to big league camp as a non-roster player, but got beat out by Gregor Blanco for the job before the latter suffered an injury the final week of March. The Dbacks used Hazelbaker for the time-being before Blanco was healthy enough to play again. The Diamondbacks have used Blanco, Hazelbaker, and Rey Fuentes as their 4th outfielder at times in the season and all three of them are likely to be around come September. That puts Arcia in basically a similar situation I outlined with Christian Walker as a LH bench bat with pop. Advanced hitting metrics like wOBA and wRC+ like Arcia more than Walker. He does have a major OPS drop against lefties, where it seems like he’s sacrificing power for contact as evidenced by a higher BA and OBP.
Arcia probably isn’t going to get a lot of starts due to the Diamondbacks pushing for the playoffs, but the team also lacks LH power on the bench. Blanco and Fuentes don’t offer much pop whereas Chris Herrmann doesn’t drive the ball in the air frequently enough although it looks like he’s seeing the ball better at the plate in recent games. It’s possible that Arcia also gets left off completely because there simply aren’t enough 40-man roster spaces to give and Hazelbaker has a decent amount of pop in his bat too and is a better defender in the outfield.