[caption id="attachment_72775" align="alignright" width="300"] Odubel Herrera is in the midst of his fourth season with the Phillies. (Ian D'Andrea/Wikimedia Commons)[/caption] Phillies Nation's Matthew Veasey may have put it best when he recently wrote that referring to Philadelphia Phillies center fielder as "mercurial" would be an understatement. For the first three seasons of his major league career, it was easier to overlook Herrera's lows, because the Phillies weren't in contention and it seemed only a matter of time before another hot-streak came. But in his fourth year, the Phillies are contending, making it harder to excuse the times where his play bottoms out and placing into question his future in Philadelphia. In any conversation about Herrera's future, it's important to start with an understanding that there isn't one perfect solution. Anyone who claims that there's an easy answer for how the Phillies should proceed with Herrera after the 2018 season is simply incorrect. A few months ago, it appeared more likely that we would be having a discussion about Herrera's National League MVP candidacy, rather than whether he should be in the Phillies plans for 2019. Herrera hit .367 in April. The 26-year-old reached base in his first 44 games in 2018, adding onto a streak that began on the final day of the 2017 season. Even after the streak was snapped in May, Herrera homered in five consecutive games in June. He wasn't ultimately voted an All-Star, though Herrera drew consideration for his second All-Star team in three seasons. https://www.philliesnation.com/2018/08/philadelphia-phillies-news-aaron-nola-2018-greatest-seasons/ However, even in a month of June where Herrera hit five home runs in a five-game span, he hit just .236 and struck out 30 times. After a pedestrian month of July, Herrera is hitting just .184 with a .424 OPS in August. In 180 at-bats since his mid-June home run streak, Herrera is hitting just .206. In the midst of the most important stretch for the Phillies since Herrera debuted in 2015, Roman Quinn has started two of the last four games in center field. At his lowest offensively, Herrera becomes a liability. Perhaps the finest month of his career was April of 2016, when Herrera hit .313 and walked 23 times, propelling him to the National League All-Star team. However, after walking 23 times in April of 2016, Herrera walked just 31 times the entire 2017 season. In 2018, he's also walked 31 times. Even if you feel that walks are being overvalued in today's game, there's no question that walking is preferable to striking out, which Herrera tends to do at an excessive rate when he struggles. Herrera struck out 30 times in June, just as he did in May of 2017, when he hit .183 in a month where the Phillies went 6-22. All the way back in May of 2015, Herrera struck out 29 times and hit just .202 after an impressive first month of his career. But that was his rookie season. Ryne Sandberg was still the Phillies manager. Perhaps the Phillies knew Herrera would always be streaky, but there had to be some hope that by the next time the Phillies were contending (which has turned out to be 2018), the lows wouldn't be quite as low. That hasn't proven to be the case. One of Herrera's other saving graces during low offensive points was that he remained an elite fielder. Between 2015 and 2017, his first three years as a center fielder, Herrera graded out as the fourth best fielding center fielder in baseball. However, in 2018, Herrera's defensive metrics have fallen off of a cliff. FanGraphs says that the former Gold Glove Award finalist has been just the 15th best fielding center fielder of 17 qualified options in 2018. He has a -7.2 defensive WAR, a -9.0 UZR and -10 defensive runs saved. Earlier this summer, I did a deep dive on just why Herrera has seen his defensive numbers fall off so drastically in 2018. Some of it may have to do with certain defensive metrics not keeping up with how frequently shifts are used in today's game. More of it probably has to do with the fact that the Phillies have Herrera using an average starting position of 321 feet from the plate, a few feet deeper than his average starting position in center field in 2017. Herrera's decline in center field may not be an especially difficult fix. It's unclear if occasional mental lapses in the field (or on the basepaths) will ever be something Herrera outgrows, but it's hard to believe that at just age 26, Herrera is incapable of covering ground in center field the way he once was. But in 2018, Herrera hasn't graded out well as a fielder, adding onto the offensive woes that he's gone through since a scorching-hot start to the 2018 season. At the same time, Herrera has the potential to carry a lineup when he gets hot. We saw it at the beginning of the 2018 season. After a disappointing first-half of the 2017 season, Herrera slashed .323/.378/.551 in the final 54 games of the season. Who's to say something won't ignite him in September, helping the Phillies to reach the playoffs for the first time since 2011? Herrera also has an all-time team friendly contract. He made $1.6 million in 2017, despite FanGraphs valuing his production at $23 million. He's making $3 million in 2018, which despite us having this conversation, is still well below the $11.8 million his production has been worth. Some have previously argued that Herrera's team-friendly deal could make him a coveted trade asset. And that's probably true. But Herrera is due just $22 million over the next three seasons, with his contract containing very affordable club options for 2022 and 2023. Between having to take care of internal players (Aaron Nola, Rhys Hoskins) and hoping to lure external superstars (Manny Machado, Bryce Harper), much of the Phillies financial flexibility could evaporate in the coming years. It's hard to think that at the rate the Phillies are paying Herrera, they could find better production. As Ruben Amaro Jr. once said when referring to Jayson Werth's future (or lack thereof) in Philadelphia, not every position player can make $10 million. Adjust the $10 million for nearly a decade's worth of inflation, and you have one of the best arguments for retaining Herrera - for what he's making, you simply aren't going to get better production. That may mean accepting some of the lows, because you would be hard-pressed to find another $3 million player that will work a 45-game on-base streak and a five-game home run streak into the first three months of a season. Who do the Phillies have that could internally replace Herrera as soon as 2019? You tell me. There's a case to be made for the aforementioned Quinn seeing increased time in center field currently, but you simply couldn't enter a season banking on him to stay healthy and be the starting outfielder. You probably wouldn't be wise, given his health history, to even expect him to be your fourth outfielder. Aaron Altherr has finally stayed healthy in 2018, but he batted just .171 in 210 at-bats. He was optioned to Triple-A Lehigh Valley on July 22, where he's hitting .262. Even despite a strong second-half, 2017 first-round pick Adam Haseley looks likely to open the 2019 season somewhere in the upper levels of the Phillies minor league system. He also seems more suited to play a corner outfield position at the major league level. https://www.philliesnation.com/2018/08/rival-gm-i-think-bryce-harper-winds-up-with-the-phillies/ The Phillies will likely enter 2019 as a favorite to reach the playoffs. It's clear that internally, they don't have an option in center field that would make them look like a better team on paper than Herrera does. Some have suggested that if the Phillies are able to sign Harper, he could play center field. Though given his poor defensive metrics in center field and that neither Rhys Hoskins or Nick Williams grade out favorably as fielders, that would seem to be a recipe for disaster. Arizona Diamondbacks center fielder A.J. Pollock is a potential free-agent, but he's had a hell of a time staying healthy throughout the course of his career. Andrew McCutchen and Adam Jones will also both be free-agents, but both make more sense in right field (where McCutchen has played in San Francisco in 2018) at this stage of their respective careers. And for as much as signing someone like Jon Jay could make sense, it would make more sense as a fourth outfielder, not a replacement for Herrera. As SportsTalkPhilly's Frank Klose said on this week's Phillies Nation Podcast, we often talk online about trading players in terms of getting rid of them. But as the Phillies hope to build themselves into a World Series contender in the coming years, if they're going to trade Herrera, they seemingly need to have a better option in center field ready to replace Herrera. And given how valuable his contract is and how dominant he is when things are clicking for him offensively, that may be a tall task for general manager Matt Klentak. Again, that doesn't mean the Phillies shouldn't pick up the phone this offseason if someone calls on Herrera - they probably should. But a more realistic scenario may be that the Phillies adjust Herrera's defensive alignment and try to tweak his offensive approach so that he walks more and some of his lows aren't quite as low. 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