Jalen Beeks | Phoenix Sports Today

Let’s look at the newest Diamondbacks’ pitcher.

Inspiration.

As you may have noticed, the Diamondbacks signed free agent left-handed bullpen pitcher Jalen Beeks. It happened a couple days after the Astros released him.

Why did the Diamondbacks need another bullpen pitcher? Likely because Jordan Montgomery needed Tommy John surgery instead of pitching in the bullpen. That injury was a huge surprise to me and likely a huge surprise to the Diamondbacks. This will be his second Tommy John surgery (the first was in June of 2018 and allowed him to pitch 5 seasons).

Why was signing Beeks a great move?

Let’s look at five reasons.

Kryptonite to the Dodgers. The last two seasons, he pitched well against the Dodgers. In the last two seasons against all teams, Dodgers’ batters had an OPS of .785, with 0.13 runs per PA. When Beeks pitched against the Dodgers (33 PAs), he held them to an OPS of .590, with 0.03 runs per PA. That’s a valid measure of Beeks’ pitching ability.

He may be kryptonite against other teams, too. In his Diamondbacks debut against the Cubs, none of his five batters faced reached base, his inherited runner did not score, and it only took him 15 pitches for five outs.

He is a candidate to be the Diamondbacks closer. Last season, Beeks was one of 35 pitchers with the most saves. This season, eight of them are in the NL West (4 with the Dodgers, 1 with Giants, 1 with Padres, 1 with Rockies, and Beeks with the Diamondbacks). Because prior to last season he never had more than two saves in a season, perhaps other teams failed to recognize his potential talent as a closer.

This AZ Snake pit article has a method to determine whether a pitcher should close for the Diamondbacks. Last season, Beeks pitched for two teams (Rockies and Pirates). Although Beeks fell just a little short of meeting two of the screening criteria (ERA and GTJD), his pitching with the Pirates met those two criteria. Making the answer uncertain is that his WPA for high leverage games was negative, albeit a small sample size. All things considered, whether he could thrive as a closer is not clear.

Last season, his fastball velocity was 94.5 MPH. For Diamondbacks’ bullpen pitchers, having velocity above 94 MPH is correlated with better results. That correlation is shown in the following graph.

His homers per fly ball steadily improved. Despite a steady worsening in his ERA, in the last two seasons his FIP stayed steady while his skill at suppressing home runs per fly ball steadily improved. These points are shown in two graphs. The first graph shows the worsening ERA.

There is more to Beek’s story than ERA. The second graph shows the steady FIP and the improvement in home runs per fly ball.

His pitching allows batters to make mistakes. As evidence, let’s look at his claim to fame, which happened on 14 May of 2022. Pitching in the top of the ninth against the Blue Jays, his pitching caused three consecutive batters (the only batters of the inning) to hit grounders to first base, allowing the first baseman to make three unassisted outs. Three consecutive unassisted outs by the first baseman is rare! Per this article, it had only happened twice previously in baseball history. Not mentioned in the article was that the other two times happened on three straight pitches, making me think the batters were not making any real effort. Beeks’ took 6 pitches to make it happen. Beeks had to really battle to achieve his claim to fame. My view is that it means more when you have to fight for it!

Summary.

Signing Jalen Beeks was a great move for the following reasons:

He is kryptonite to the Dodgers.
He is a candidate to be the Diamondbacks closer.
Last season, his fastball velocity was 94.5 MPH, which is positively correlated with better results.
In the last two seasons, his homers per fly ball steadily improved.
His pitching allows batters to make mistakes.