Facing a weak schedule in the days ahead (WAS, FLA, PIT), many perceive Omar Minaya as having time to assess his roster and make a trade. With Delgado, Perez, Reyes, and Church out for indeterminate amounts of time, there's flexibility (a bad kind) on what position to target. To make the best possible move, however, Minaya needs to take an honest stock of the current roster and commit to a few players.
First off, Sheffield will probably start most of the rest of the year in right or left. I resisted that idea early in the season, mostly because of his fielding and Church being around, but he's been the second best hitter on the team so far, without totally embarrassing himself in the field. His ZiPS rest-of-season projection calls for a .763 the rest of the way, but that assumes a massive drop-off in plate discipline that seems very unlikely. Whether it's age, a return to the NL, or both, Sheffield has been the most patient hitter on the team and can probably be counted on to give something around a .360 wOBA (~.810 OPS) for the rest of the season, which seems just as good as anything we can reasonably expect from Church or F!. In the field, UZR has him at 2 runs below average so far, 1.4 of that being his arm. Granted, 21 games in the field is the rough statistical equivalent of 7 at the plate, so it's not very predictive of future performance. Still it's encouraging, and so far he's been worth .7 WAR, a 2.8 million dollar return on Omar's original investment.
On the shortstop front, Cora plans to return on Tuesday. With Reyes also figuring to return in about a week when he's eligible to come off the DL, the team can probably forge ahead on the Martinez/Valdez express for the next few days.
At firstbase, Delgado is tentatively scheduled to return in 9 weeks, assuming rehab goes well. I want to believe Daniel Murphy can provide the offense/defense necessary, but that's a risk, and not one the Mets need to take. Another big argument against trading for a firstbaseman is that Carlos Delgado will have to sit when he eventually does come back. Maybe that's not a bad thing. Having another, presumably better, firstbaseman would allow Delgado to take his time coming back. Also, it's anyone's guess what he does on the field when he comes back. His ZiPS rest of season projection is .363 wOBA, which is decent, but hardly guaranteed coming off injury. Many people cited lingering injuries as the reason Delgado tanked in the first half of 2008.
For that reason, Nick Johnson seems to be the best fit at first. He's definitely better than Delgado, healthy or not. He's a consistent .400 wOBA (.900 OPS) hitter with great plate discipline and good range at first. He's affordable, at $5.5MM, and DING DING DING, a former Expo. He's in the walk-year of his contract and his value will be seriously tempered by his bad history with injuries. Since they play in the NFL, the Nationals have wisely decided to focus only on pitching prospects, and Parnell, Antonini, Kunz, and Gee have been some names thrown around. Parnell should and will probably stay, with Putz still looking shaky in the set-up role. If the Mets can get Johnson for any combination of Kunz, Antonini, or Gee, however, they should do it. Niese would probably fall in the same category as Parnell, as he'll be needed down the road. Antonini and Gee profile as back-end starters at best, 1-1.5 WAR players the Mets can probably find elsewhere. Kunz, a middle reliever who gets groundballs, but does nothing else right, is essentially worthless, with his upside being virtually worthless. If the Mets can trick the Nationals into thinking he's a closer in the making, they should push hard to get the deal done. Assuming 300 PA and each firstbaseman playing to expectation, Johnson could be roughly a 2 win improvement over Delgado. The biggest knock on Johnson, his health, would be mitigated by Delgado being on the bench. I know it hurts some people to imagine paying a bench player $16MM, but depth would be worth it in this instance.
Aubrey Huff is another popular name, but he's not half the player Johnson is. Even with his anomaly season last year, Huff has a career .827 OPS, and that's how he's played so far this season. Combined with his poor defense at first, the Mets could probably get the same, maybe even better, production out of Murphy. Another argument for Huff has been his ability to "play" the outfield, but if the Mets really want an outfielder they should get a real one, and I'll cover that more in Part 2.
Adam LaRoche is strikingly similar to Huff, except he may be a worse hitter. He's another guy that probably wouldn't be a huge upgrade over Murphy and certainly not worth the $7 Million or so he's due this year.
I'll cover Mark DeRosa with the outfielders. Request any firstbasemen I forgot in the comments and I'll cover them, too.