2017 season review: Durham Bulls relief pitchers

The Durham Bulls had many relievers start the season that were on the cusp of helping the Tampa Bay Rays bullpen. Jaime Schultz, Ryne Stanek, and Andrew Kittredge were expected to spend time riding the Durham Shuttle and getting their opportunity to take hold of a MLB bullpen roster spot. Schultz’s injury early in the season necessitated the move of Chih-Wei Hu to the bullpen. Jose Alvarado and Diego Castillo started the season in Double-A, but were among their high leverage arms.

The bullpen carried a heavy workload and put up results.

The bullpen of the Durham Bulls were a big reason they were able to go 86-56 (a 98 win pace over 162 games). They covered 42.9% of the innings thrown by the pitching staff. The Tampa Bay Rays bullpen covered 37.8% of the innings thrown by the Rays.

Multiple inning relievers were leveraged to cover the innings. Schultz was the only reliever with more than ten appearances who threw less innings than appearances with many being well above as they averaged over four outs per appearances.

The biggest question surrounding Durham’s pitching coach Kyle Snyder’s promotion to the same position with the Rays is whether the multiple inning bullpen usage was necessity or philosophy.

As a group, the relievers struck out a well above average 29.0% of batters. They walked a few more than average, but were well above average in every other category.

Individual Performances

32 players threw a pitch out of the bullpen for the Bulls including three position players (Michael McKenry, Johnny Field, and Kean Wong). Seven pitchers accumulated at least 40 innings. 14 pitchers threw less than five innings split between guys called up when the Durham bullpen needed someone after the Rays called up a reliever due to injury, under performance, or needing a fresh arm.

Andrew Kittredge was used mostly in high leverage situations after coming over from Seattle this past winter, while also providing multiple innings with 62.2 innings in 39 appearances. His 31.1% strikeout rate and 6.7% walk rate led to great results with a 1.29 ERA and 2.18 FIP.

Jeff Ames received the second most innings, with 58.1 innings of 4.17 ERA and 4.02 FIP. Ames had bouts of wildness with a 12.9% walk rate. He did strikeout 28.6% of batters, but the results were hit and miss.

Ryne Stanek finally put up results that you would expect out of a reliever who sees triple digits on the radar gun with great frequency. His 34.5% strikeout rate and 9.2% walk rate led to a 1.21 ERA and 1.79 FIP. He was the high leverage arm the front office has shown faith in despite sub par results. Now the only thing left is to translate these results to the majors in a large sample.

Adam Kolarek was the most used left handed pitcher in the bullpen. He threw 43.2 innings with a 1.65 ERA and 2.54 FIP. A 25.0% strikeout rate and 8.7% walk rate earned him his first MLB appearance this summer.

Chih-Wei Hu transitioned to the bullpen after making three starts to open the season when Jaime Schultz went down. He had a 24.7% strikeout rate and 5.6% walk rate. In 27 relief appearances he threw 43.2 innings with a 2.89 ERA and 4.07 FIP. He threw multiple innings in almost every outing, but didn’t receive more than two appearances in a week. Two-to-three days off was common, but there were times he went a week between appearances.

Diego Castillo built off his impressive showing in the Arizona Fall League last season. He started the season in Montgomery (Double-A), but in early July he received the promotion to Durham. He was one of the most used arms down the stretch with 29 relief appearances totaling 41.2 innings with 3.46 ERA and 2.48 FIP while making one start. By the end of the season Castillo was the Bulls highest leverage reliever. In the Triple-A National Championship game Castillo closed a four out save opportunity.

Overall it was a promising season for prospect relievers.