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Fixing the Phillies’ Bullpen

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Yes, it is possible.

Robert Stephenson
Kareem Elgazzar/The Enquirer

Putting it bluntly, the Phillies’ historically-bad bullpen needs to undergo a major rebuild if the team expects to contend in 2021. There are a plethora of established free agent options whom the Phillies can entice with their sizable payroll flexibility. Signing multiple lockdown relievers seems to be the front office’s first step in building a competent bullpen.

In reality, the problem is much deeper than this. Despite what you may think, the Phillies’ failure to acquire capable relief arms does not stem from lack of talent in the front office. The true cause is the prevalence of a misunderstood philosophy about what it means to construct a Major League roster while utilizing a $200 million payroll.

My next article for TGP will go into further detail about what I just said. But for now, I am going to focus on what it is the Phillies (or any team, really) must do in order to rebuild their bullpen.

Let’s start by taking a quick look at who will be returning next season. I expect Hector Neris and David Phelps back on guaranteed salaries with Connor Brogdon, Ramón Rosso, JoJo Romero, and Victor Arano all in the mix as well. It should be noted that Vince Velasquez, Heath Hembree and Adam Morgan will be under club control for 2021, however all three are at risk for being non-tendered. Overall, there is certainly plenty of room for improvement.

In terms of building the 2021 bullpen, the question is not who the Phillies should acquire, but rather what they should acquire. For example: the Rays picked the Phillies’ pocket last offseason when they signed John Curtiss and turned him into an electrifying late-inning arm. What the Phillies saw in John Curtiss was a pitcher with a 7.75 AAA ERA, and he was promptly released by the team for that reason. What the Rays saw was a devastating fastball/slider combo belonging to someone who just needed minor adjustments in order to become a great big league reliever. More importantly, the Rays’ cost to acquire Curtiss was basically nothing.

Herein lies the path to success. Teams don’t need to shell out tens-of-millions of dollars to relievers who may have already reached their peak. The goal should be to identify the potential in relief pitchers (or any player) and strike while the acquisition cost is low. There is a sea of relievers out there who have downright elite stuff. It is up to the front office to find them and the player development staff to make them to reach their potential. Yes, this is a small market philosophy, but I believe every club should be run using small market ideologies, no matter the payroll size.

Moving onto the task at hand — finding undervalued relievers.


I’m not going to go into explicit detail about my process for quantifying these players. In short, I used “stuff” metrics (velocity, movement, spin, etc.) to model whiff and ground ball rates for different pitch types. I then combined these rates into one grade for a given pitcher. By boiling my findings down to one number, I essentially created a metric that evaluates a pitcher’s total arsenal. I did two separate calculations for whiff and ground ball ratings because not every pitcher goes for whiffs and not every pitcher goes for ground balls. For the remainder of this article, a pitcher’s Arsenal xWhiff% and xGB% ratings will be denoted as “AxW” and “AxGB”, respectively. Here are the calculations for each rating:

1 denotes the first pitch in a pitcher’s arsenal, 2 denotes the second, etc.

This equation takes into consideration the pure expected whiff/GB rate of each pitch, the comparison of that rate to the rates of other pitches of the same type, and the usage of the pitch. For simplicity’s sake, I converted the final ratings into percentiles for every pitcher. Here is the layout of percentile ranges, with some key reliever examples:

It is rare that a pitcher does well in both models. For example: Aaron Bummer is the highest rated pitcher according to the ground ball model, and the seventh-lowest rated according to the whiff model. This goes for most sinker-reliant pitchers. Here is a visual of how the Phillies’ 2020 staff graded out:

While the Phillies have a few pitchers ranking in the top 25% for at least one rating, no one is in the top 10%, meaning the team has no pitchers who possess top-tier stuff.

Time to move onto the external candidates who I believe have late-inning, high-leverage potential, according to my models.

Relievers who will require Major League deals

The team will need to bring in established pieces to bolster the back-end of the bullpen immediately. The models favor the following six impending-free agents:

Among free agent pitchers who are destined for guaranteed contracts, Trevor Rosenthal (97th percentile AxW) stood out most in my findings. Despite his 2020 dominance, Rosenthal will be 31 next season and faces an uncertain market due to injury history and pre-2020 struggles.

Blake Treinen (97p AxGB) and Trevor May (93p AxW) could both be in-line for multi-year deals. While I would explore other options before simply handing out a multi-year contract, if the front office is looking to bring in someone on such a deal, then these two would be my top choices.

Other established relievers who will likely require Major League deals are Greg Holland (90p AxW) and T.J. McFarland (96p AxGB).

It is now time to examine which relievers the models deem to be undervalued. I will mostly analyze low-cost free agents, non-tender/DFA candidates, and certain trade targets.

Almost every pitcher I list from here on out struggled statistically in 2020, which is a main reason why I want them to be considered. Pitchers with great stuff and good statistical performance are going to have high price tags, especially for a team like the Phillies who lack substantial trade capital. I am also not going to go into detail on every single pitcher, only the ones who I would truly emphasize if I were a part of the front office.

Relievers who will require minor league deals

Oliver Drake (96p AxW) was recently DFA by the Rays, and subsequently elected free agency. On top of his 2020 struggles, Drake will be 34 next season, making him a prime candidate for a minor league deal. The strength of Drake’s arsenal mostly comes from his screwball (listed as a splitter), as it is one of the most interesting and dominant pitches in the game.

Matt Magill (97p AxW), Hector Rondon (86p AxGB), and Dominic Leone (79p AxW) were all recently released by their respective clubs and will only require minor league deals for 2021. Jared Hughes (95p AxGB) likely did not pitch well enough in 2020 to warrant a guaranteed deal, making him a good fit as well.

Non-tender candidates, DFA risks, and other low-cost options

This is the biggest and most important group that I cover. While low-cost free agents are certainly enticing, their acquisition is dependent on open-market competition. The following players are under club control for next season so their most likely acquisition route is trade.

One caveat with these players is they are all at-risk for being non-tendered or designated for assignment ahead of the 40-man roster deadline next month. If a team knows they are going to have to release a player under these circumstances, their best move is to trade them for literally anything. Because of this, teams looking to unload such players will have minimal trade leverage, making the Phillies ideal partners. Moving onto the players:

Robert Stephenson (98p AxW) was quietly one of the best relievers in baseball in 2019 but now finds himself on the roster bubble in Cincinnati after an injury-plagued 2020. Stephenson will be arbitration-eligible next season and is therefore at risk of being non-tendered by the Reds as they attempt to slash payroll. I should also note that he is out of options. Stephenson has been on my radar for some time and right now is potentially the opportunity to make a run at him.

Much of what was said about Stephenson can also be said for Hansel Robles (75p AxW). Robles has one year of club control remaining and there is a high chance he could be non-tendered by the Angels after a disastrous 2020. The Angels could also be willing to part with Keynan Middleton (93p AxW) as they too look to rebuild their bullpen.

Luke Jackson (98p AxW) was left off the Braves’ playoff roster, indicating his poor standing in the Atlanta bullpen. He will be arbitration-eligible and could be a 40-man crunch victim. Pittsburgh’s Dovydas Neverauskas (77p AxW) is very likely to be non-tendered. He has struggled in each of the last 3 seasons and looks primed for a fresh start.

Franklyn Kilomé (80p AxGB) is out of options and the Mets may have no choice but to explore trades for him. Ground ball threat John Schreiber (97p AxGB) could be jettisoned by the Tigers as they continue to rebuild.

A trio of Red Sox in Marcus Walden (98p AxGB), Robert Stock (86p AxW), and Colten Brewer (94p AxGB) are also on the roster bubble heading into the offseason. It is unlikely all three survive the team’s impending roster crunch.

Josh Osich (92p AxGB), Robinson Leyer (87p. AxW), and James Pazos (91p. AxW) have already been outrighted off their respective teams’ 40-man rosters and therefore will have minimal acquisition costs.

Trade candidates

San Diego’s Pierce Johnson (99p AxW) jumped out on my model, largely due to the strength of his curveball (48% xWhiff%). Johnson stepped up last season when the Padres’ bullpen dealt with injuries, however he is certainly not untouchable in trade. If the Padres add a big-name reliever to group with Drew Pomeranz and Emilio Pagan, there may not be a major reason to keep Johnson. He has a $3 million club option next season that could be exercised and he does not hit free agency until 2026.

Cincinnati’s Lucas Sims (99p AxW) has one of the best fastball/curveball combinations in baseball, according to this metric. Sims seems primed for an increased role in the Cincinnati ‘pen, however he will still be competing with Raisel Iglesias, Archie Bradley, Amir Garrett and Tejay Antone for innings. The amount of depth in the Reds’ bullpen plus the fact that Sims is out of options makes a trade possible. Sims is only 27 and not scheduled to hit free agency until 2025.

Lefty Jose Alvarado (99p AxGB) has fallen out of favor in the Tampa Bay bullpen and could be on the move as he approaches his first year of arbitration. Alvarado was one of the best young relievers in baseball in 2018 and will only be 26 years-old next season.

There are many trade targets beyond Johnson, Sims, and Alvarado who I am going to quickly mention but not go into explicit detail on. The going rate for each reliever depends on a multitude of factors, but none of them are considered untouchable. These players include Adam Kolarek (99p AxGB), J.P. Feyereisen (92p. AxW), Matt Barnes (91p AxW), Chasen Shreve (90p AxW), and Josh James (90p AxW).


I mentioned the names of over 30 relievers for a reason. Narrowing one’s sights on 3-4 players will not fix the problems that plagued the Phillies’ bullpen last season. Simply opening the check book and bringing in already-established relievers with the hope that they can continue their strong performances is not the answer. Finding value in the undervalued is what leads a team to success, not their payroll.

Obviously, the team will not bring in every single one of these relievers. The front office may not acquire any of them. The point is in order to build a dominant bullpen, you need to be willing to look far and wide at all possible options. There is a sea of talented relievers out there who are not currently getting enough opportunities to shine. I just highlighted a small fraction of them.