Daniel Ponce de Leon is a pitcher who has been around the fringes of the Cardinals roster since making his debut in 2018. He has been able to help himself by playing a number of different roles for the team as he has started 20 games and made 13 appearances out ofthe bullpen, while even serving as the closer in one game. However, while this flexibility can be helpful for the Cardinals, the team would be able to get better production from the right hander if he became a full time member of the bullpen.
To begin with, Ponce de Leon has struggled to keep his pitch counts under control when he starts games. Last season, Ponce de Leon average jut over four innings per start, while in the season before, he averaged 4 1⁄3 innings per start. This is clearly not very good, and this can cause the bullpen to be overworked. Part of the reason why Ponce de Leon has been unable to pitch deep into games, is because he struggles when he has to work through a lineup multiple times. In his career, Ponce de Leon has posted a 3.16 ERA and 3.48 FIP in his first time through the opposing lineup as a starter. However, in his second time through the lineup, he has struggled to the tune of a 4.89 ERA and a 5.25 FIP. Additionally, in the rare occasions that Ponce de Leon has seen a lineup three times, he has done even worse (6.23 ERA, 6.19 FIP).
Ponce de Leon has only thrown 114 1⁄3 innings in his career, so this is still a bit of a small sample size. However, the trend is clear - Ponce de Leon struggles when he has to face a lineup multiple times. Additionally, 61.1% of Ponce de Leon’s pitches last season were fastballs, while his percentage of fastballs was even higher in 2018 (70.7%). With such a focus on one pitch, Ponce de Leon might struggle to face hitters multiple times when they have already seen his fastball and know that it is coming. If he moves to the bullpen, then this would not be a problem, and his fastball may even gain couple ticks.
Additionally, Ponce de Leon has struggled to establish his secondary offerings throughout his career. The 29-year-old was more confident in his changeup when he first debuted, than he was in 2020 as it’s usage rate has dropped from 16.5% to 3.9% in that time. However, in exchange, the usage rate of his curveball has risen from 3.1% to 21.7% in that time. The confidence that Ponce de Leon seems to have found in his curveball would allow him to simplify his arsenal to mostly fastballs and curveballs with a few cutters as a tertiary option (13.3% usage rate in 2020).
This would give Ponce de Leon a high spin fastball (70th percentile, 2354 rpm) to pair with a high spin curveball (69th percentile, 2671 rpm) that could act as the primary breaking/off-speed pitch. The right hander has generally experienced good results with these pitches,as his curveball has been effective since he really began throwing it in 2019, and his fastball was effective in both 2018 and 2019, before falling off a bit in 2020. However, part of the reason for this drop in 2020 could be that Ponce de Leon was almost exclusively a starting pitcher in 2020. Given the amount that he throws this pitch, and his struggles when he faces a lineup multiple times, this is not too worrisome. Thus, it is likely that his effectiveness with the pitch will return to normal levels if he is turned into a full time reliever.
Ponce de Leon also generates above average vertical and horizontal movement with both pitches, which adds to the attractiveness of using them in tandem in a bullpen role. With more focus on these pitches, and less of focus on his average-at-best cutter and his fringy changeup, Ponce de Leon may be able to improve his two primary pitches. Adding a few ticks to his fastball which already experiences 10% more rise than the average fastball would also make the pitch even more impressive.
Even without such an improvement, Ponce de Leon was able to generate a 34.4% whiff rate on his fastball in 2020, which was an improvement to the still strong 28.3% that he generated in 2019. Additionally, Ponce de Leon does not generate as many whiff with his curveball, but he does generate plenty of weak contact (.122 wOBA in 2019, .253 wOBA in 2020). Thus, using these pitches in tandem and limitign his usage of his other pitches, while also throwing just one or two innings at a time may increase Ponce de Leon’s production. This is even more important considering that he does not have any more minor league options. Therefore, a change in role may allow Ponce de Leon to improve, and also solidify his spot in St. Louis.