It is just one week of a season, but does this one week encourage you that the Mets are contenders this season? For you do not waste your best starting prospect in middle relief on a non-contender.
It may be too early to label the Mets as a non-contender, but there are still plenty of reasons to question Mejia's use in the bullpen. We are all familiar with the reasons why Mejia belongs in the minors. He has front-line starter potential, is only 20 years old, needs work on his secondary pitches, and has had little experience in Double-A or above. Ignoring these arguments, the Mets -- and some beat reporters, like Kevin Burkhardt -- suggested that Mejia should make the major-league team because he can help the Mets win now. Ergo, Mejia made the Opening Day roster. But are the Mets actually using Mejia to win games?
Not really. If we take a look at Mejia's Leverage Index for his three apperances this year, we can see that he's been used exclusively in low-leverage situations. His average Leverage Index - called pLI - is at .40 (an LI of 1 is considered a neutral situation). Mejia's pLI tells us that he's being used when the balance of the game is not really in question. Looking at the game situations Mejia has pitched in confirms the data:
April 7 - Enters game in 6th inning with the Mets down to Florida 4-1.
April 9 - Enters game in 9th inning with the Mets ahead of the Nationals 8-2.
April 10 - Enters game in 9th inning with the Mets down 4-3.
In Mejia's first two appearances, he did not enter the game in anything close to resembling an important situation. More was at stake in Mejia's last appearance, coming with the Mets down one run in the ninth, but that situation only registers a 0.7 on the Leverage Index scale (according to this Leverage Index table). What Mejia has not done is enter a game when the Mets have had a small lead or there were men on base, i.e. high leverage situations in which Mejia could help the Mets win games. Rather, he's being used as a run-of-the-mill middle reliever.
If the Mets' main reason to put Mejia in the bullpen was to "win now," Manuel's use of Mejia in the first week of the season suggests otherwise. Given the strong performance of the bullpen thus far (21.1 innings, 1.27 ERA), the Mets probably have no need to use Mejia in higher-leverage situations, and will likely continue to defer to Nieve and Feliciano in such situations. If that's the case, then the Mets need to replace Mejia with whoever's next in line at Buffalo (Parnell, most likely).
Of course, the Mets will probably refuse to demote Mejia until he implodes or the Mets fall significantly below .500. I don't want to hope for either of those things to happen, but at least Mejia going back to the minors will be the silver lining of either of those occurrences.