D-backs Need More Velocity and Strikeouts from Bullpen

While improvements were made in 2023, the large velocity and therefore strikeout deficit from relievers persists

Following the 2022 season Diamondbacks pitching coach Brent Strom made an appeal to the organization to add more velocity to bullpen. The Diamondbacks were coming off a season in which they once again ranked near or at  the bottom in both fastball velocity and strikeout percentage from the bullpen. That had been the case nearly every season since Mike Hazen took over as GM in 2017.  That situation only improved marginally in 2023, as can be seen in the table below. 

To be clear, pitching is not only about velocity, even from the bullpen. Disrupting timing with at least one good secondary pitch, and above all else, having good command are essential elements. That said here is no denying the relationship between velocity and strikeouts, which are critical to get in big situations late in games.  

The lack of improvement in this area wasn't for lack of trying, as the team attempted to add velocity.  Prior to the 2023 season they signed veteran Miguel Castro, who owned a 98 MPH sinker and a power slider. They traded for Carlos Vargas from the Guardians organization, a pitcher that can reach triple digits on the radar gun with his four seam fastball and averages 99.  

At the same time prospect Justin Martinez was sent to the Arizona Fall league to hone his 100+ MPH fastball and splitter/slider repertoire, which he did with great success, creating a lot of excitement heading into spring training.  Luis Frias was another prospect with a fastball in the upper 90's that had already appeared in games for the D-backs on 2021 and 2022, but had yet to harness his stuff, leading to extremely high walk rates. 

None of these efforts worked out in 2023. Castro often struggled with walks or falling behind in counts, leading to big home runs from mid June onwards, and into the postseason.  Vargas had a good spring and made the opening day roster, but pitched in only five games, walking four in 4.2 innings, giving up three runs. Unable to earn his manager's trust, he was optioned out to Triple-A Reno on April 11th and never made it back to MLB in 2023. He walked 32 in 42 innings while posting a 7.02 ERA for the Aces.

Martinez earned his first of three call-ups on July 17th. While he provided some electric moments, lighting up the radar gun as high as 102-103 MPH and averaging 100.5, he seldom knew where it was going. He recorded 14 strikeouts in 10 innings, but that came with 11 walks, 13 hits, and 14 earned runs for a 12.60 ERA. He did not pitch in the postseason.

Frias showed some improvement at times through his multiple call-ups, posting a 4.06 ERA in 31 innings. He walked 17 and struck out 26. He also pitched  6.2 postseason innings, giving up four runs, one earned, walking three and striking out eight. Frias averages 96 MPH with his fastball and his growth was probably the most encouraging out of these four pitchers. He's still very much a work in progress however. 

There is still hope for Vargas (24 years old), Martinez (22), and Frias  (25), as they're quite young. It's just that to date the organization has not had success developing hard throwers that can throw strikes.  One other young pitcher on the horizon to keep an eye on is 22 year old Yilber Diaz who has a fastball that ranges between 95-98.  He was a starting pitcher in Hillsboro and Amarillo last year, but could end up in the bullpen down the road. He had 140 strikeouts in 103 innings. He also walked 58. 

Getting outside help while waiting for one of these young fireballers to figure it out is difficult, as evidenced by the Castro situation. It might be tempting to suggest the team go out and try to sign an established hard thrower, such Aroldis Chapman, who is projected to get two years, $24M on the open market this year.  That average annual is probably well above what the team would look to spend for a bullpen upgrade however. 

Reynaldo Lopez averages over 98 MPH on his fastball and posted a 3.27 ERA for three teams last year, and also posted  a 2.76 ERA for the White Sox in 2022. He is projected by MLB Trade Rumors to get three years, $30 M in free agency.  Robert Stephenson, the former Rockie and Pirate, throws 97, and posted a 3.10 ERA. He's projected to get four years, $36 M.  All of these seem outside the D-backs price range however.  Joe Kelly, whose $9.5M option was declined by the Dodgers,  might be somewhat less expensive, but brings some potential clubhouse issues with him. 

One 2023-24 free agent who wouldn't cost as much as the options mentioned above is former Diamondback Keynan Middleton. He throws a 96 MPH fastball and has a good changeup. Pitching for the D-backs in 2022, he  got into 18 games posting a 5.29 ERA. Still it was somewhat of an eyebrow raiser when he was let go at the end of the year, due to owning good stuff and prior success in the majors.  He  went on to post good numbers for the White Sox and Yankees in 2023. In 51 games, 50.2 innings he had a 3.38 ERA and a whopping 64 strikeouts against 23 walks.  He did give up eight homers, but he was still an arm the D-backs could have used in 2023 and might consider in 2024. 

With limited budget, and internal options that have not yet panned out, Mike Hazen's baseball operations team will need to be creative in trying to close the gap in this critical area. Since bullpen was not emphasized as much as starting pitching by Hazen when stating his wish list priorities  there might not be early or even any movement this offseason. That said it's hard to imagine he won't try to improve the bullpen. Strom will be hoping that comes from hard throwers that can actually throw a strike and mix in their breaking pitches in the proper sequences. 

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