D-backs Top 40 Prospects in 2024: No. 21 Spencer Giesting

The left-handed starter had a standout season as he made his name appear on the top prospect lists with his play

The Amarillo Sod Poodles host the Arkansas Travelers in in a Texas League Championship game, Tuesday night, September 26, 2023, at Hodgetown, in Amarillo, Texas. The Arkansas Travelers won 6-5. / Carter Pirtle for the Amarillo Globe-News / USA TODAY NETWORK

This article is part of a series reviewing the seasons of the top 40 prospects still in the Arizona Diamondbacks system as of the end of 2024.

Spencer Giesting, LHP, Starter, DOB: 07/02/2001, 6'4, 200

Acquired: 11th Round Pick of 2022 MLB Draft, No.318 Overall

Left-handed starting pitcher Spencer Giesting was taken in the 11th Round by the Arizona Diamondbacks out of UNC Charlotte which gave him a huge over-slot deal. He received a bonus of $400,000 despite being past a 10th-round pick where the max was $125,000 before it affected the bonus pool.

Giesting pitched solely in High-A Hillsboro for 2023 and had a normal season without much surpassing of expectations or underwhelming display of pitching.

That's why the team had him start back at High-A with the Hillsboro Hops for the 2024 season. The second season playing in Hillsboro worked like a charm as Giesting dominated opposing hitters there.

Over 10 games, Giesting pitched to just a 1.50 ERA, 60 innings, 39 hits, 13 walks, and 67 strikeouts. His FIP was 2.53 and his xFIP was 3.03. He pitched six or more innings in seven of the starts, routinely reaching seven. His WHIP was an obscenely low 0.867. The breakout season was in full effect.

On June 18, he was given the much-deserved promotion to Double-A Amarillo. With the Amarillo Sod Poodles, Giesting's low 90's pitches struggled a bit.

Over 15 games and 81.1 innings, Giesting recorded a 4.65 ERA with 84 hits allowed, 31 walks, and 87 strikeouts. The strikeout ability from his low-80s slider was working well as it's by far his best pitch.

Truly, he had three bad starts in Amarillo that inflated his ERA. All three of those starts, he gave up six or more runs. In the other 12 starts, he allowed four or less and in nine starts, he gave up two earned runs or less.

With the Sod Poodles, his FIP was 4.27 while his xFIP was 3.71 indicating that he had a decent amount of bad luck that contributed to his elevated ERA.

Giesting seemed to figure it out over his last five starts of the season. Over his final 27.2 innings, Giesting had a 2.60 ERA with 25 hits given up, just four walks, and 36 strikeouts. He gave up just two home runs in a wild offensive league. It was a great finish to the season.

He needs to manuever his low-90s fastball around the zone with pinpoint command in order to keep the barrel off of it and obtain the swing and miss he wants.

He throws an upper-80s cutter and a upper-70s curveball that both flash above-average potential if he can learn to harness them better, but his ability to spin the ball is already quite good. He's shown a penchant for spinning the ball wherever he wants it to be.

His slider has a 60-grade already and could climb even higher as he develops while his curveball grade is 45 and his cutter is 50. All three of those pitches could become above-average eventually and help him climb faster towards Chase Field.

There were a couple of concerns that will have to be addressed and fixed in Double-A next year. He got ground balls at just a 40.9% rate in Double-A, almost six percent lower than High-A.

He walked batters at 8.7%, an increase of 3.1% from High-A while he struck out batters just 24.5% of the time, a decrease of 4.3%. That can be attributed to the batter's ability to lay off pitches, but Giesting has to overcome that to continue moving up the ladder.

2025 Outlook

Overall, Giesting could be in the Majors a lot sooner if the team moves him to the bullpen where his sweeping pitches can work even better in short stints and his fastball might get a couple more MPH on it above the 91 average max he already reaches.

That would enable him to be quite an effective reliever. However, the team is certainly going to give him plenty more time as a starting pitcher considering how he's done thus far.

Expect Giesting to stay in Double-A to start 2025 and if he can lower his ERA some more while maintaining the strikeout rate he has and throw more strikes in the future, he has a shot to reach Triple-A by the end of next season.

If he does all of that, it wouldn't be a surprise for the Arizona Diamondbacks to promote their breakout prospect, Spencer Giesting, to Triple-A come mid-season.