The Mets bullpen has the potential to be incredibly good. Possibly one of the best in baseball. That feels weird to say after it was the team’s Achilles heel in 2019, but possible bounce-backs from both Edwin Diaz and Jeurys Familia, the return of Brad Brach, the acquisition of Dellin Betances, and Seth Lugo’s emergence creates an array of horrifying late inning scenarios for opponents.

That being said, building a bullpen should never stop. They are like organisms: breaking- down, moving, and changing with every turning day. Lugo still has a flimsy UCL, Betances is coming to Queens with a laundry list of injuries, and there is no telling which Edwin Diaz will show up in 2020. There is a chance the collective is great, but the variance is high.

Brodie’s job with this bullpen is not done, especially with only one left-handed option, and here are two potential low-cost, high potential relievers the Mets could take a look at.

Francisco Liriano

Liriano’s first season working as a reliever was mildly successful. He was 5-3 with a 3.47 ERA, 4.53 FIP, and 63 Ks in 70 IP. Very meh, nothing exciting here.

He enjoyed a slight bump in velocity across the board from 2018 to 2019. Nothing to write home about, but an improvement nonetheless.

(Source: FanGraphs)

Where Liriano was elite was in limiting hard contact. He was in the 98th and 96th percentiles in opponent’s exit velocity and hard hit rate. Specifically against left-handed hitters, Liriano only allowed 17 balls in play (1.5%) greater than 95 mph exit velocity, the benchmark number that qualifies ‘Hard Hit Rate’.

Regardless, Liriano was still unable to miss bats. He only struck out 20.9% of the batters he faced and his 11.9 BB% was in the bottom 9% of the league. His K-BB% (9.3%) ranked 205th out of 249 RPs who threw at least 30 innings.

A peak under the hood shows that Liriano’s changeup and slider missed plenty of bats. His fastball is not shown below since he threw it less than 6% over the final three months of the season:

More than just whiffs, the difference in effectiveness between Liriano’s pitches was stark in 2019.

(Source: Baseball Savant)

If Liriano refocused his repertoire to feature his changeup and slider, he could develop into a late-inning weapon.

Robbie Erlin

Another former starter, the early stages of Erlin’s career were marred by injuries and ineffectiveness. He has never completed a season with an ERA under 4.00 and only threw 32 2/3 innings from 2014-2016. Lingering elbow issues ultimately resulted in Tommy John surgery May of 2016. He missed the entire 2017 season before switching to a relief role full time midway through 2018.

Erlin has never blown anybody away with his 90 mph fastball, but is true control artist.

(Source: FanGraphs)

Pounding the zone without elite velocity is all good and well, but Erlin’s potential derives from his exceptional curveball.

When throwing his curve last season, Erlin surrendered no walks and struck out more than 30% of opponents. They hit only .182 BA (.204 xBA) against it with a measly .176 wOBA. Batters hit above .300 with at least a .337 wOBA against all 4 of his other pitches.

The pitch is menacing, especially compared to the rest of his arsenal, but Erlin has never featured it. He had just the 252nd highest breaking ball percentage in baseball last season (40th percentile). He threw all five of his pitches at least 10% of the time despite the ineffectiveness of four of them. This is the pitch-mix of a starter, not a reliever.

                                         (Source: Baseball Savant)

The Padres deployment of Erlin may be the cause of his balanced repertoire. Erlin threw more than one inning in 35 of his relief appearances dating back to 2018 opposed to 28 of one inning or fewer. Former starters can give you length out of the pen, it is a tale as old as time, but this old-school adage may be keeping Erlin from his potential.

(Source: FanGraphs)

Erlin’s has some serious strengths, but has not yet pitched to them. A series of minor adjustments can make him tremendously valuable.

Both Liriano and Erlin can be signed with little to no risk. Both come with starting experience and can likely be stretched out if absolutely necessary. Both are teeming with potential, much like the Mets’ bullpen.