Battling Bucs : The Barmes/Mercer Debate

The weakest position in the Pirates lineup is clearly shortstop. Clint Barmes began the year as the starter but recently has been yielding playing time to Jordy Mercer. When it comes to the fan base Mercer is the popular choice to handle the shortstop duties because he has a better stick but once you factor in defensive values most metrics say there is likely to be at most one quarter of a win difference between the two over the remainder of the season. That is really insignificant.
The bottom line here is that neither player is really a good option. Teams usually aren't going to have great options at every position but they need to be a little bit more attractive than what the Pirates currently have. Take RF for example, that is probably the Pirates 2nd biggest weakness currently but Snider, Tabata and Sands are all at least interesting players who have the potential to be good options. Barmes and Mercer on the other hand are like Alex Presley a perfectly acceptable bench option but not exactly someone you want to count on starting everyday. The solution is to upgrade the position but that is unlikely to happen this year. The potential trade market for shortstops looks pretty barren with the only attractive potential options being Jimmy Rollins and Alexi Ramirez. It can't even be assumed that the Phillies or White Sox will sell but if they don't the market only gets worse. A guy like Nick Punto from the Dodgers interests me but that is more due to his ability to play 2B and 3B and hit lefties well as he is no longer an everyday shortstop option.
So fixing the spot by trade is unlikely to happen. That leaves internal options but outside of Mercer and Barmes the only other real option is Chase d'Arnaud and he really is just more of the same. He has some nice tools but overall really isn't starting material. Josh Harrison and Ivan De Jesus are also down in AAA but they are like Garrett Jones and Brandon Inge are in the outfield. Guys who can sort of play the position but who you don't want there for an extended time period. Realistically upgrading the shortstop position this season either externally or internally isn't going to happen.
That leaves us with Mercer and Barmes as really the only options. There are compelling cases for each one. The best case for Barmes is that he probably isn't really as bad at the plate as he has been so far this season. He got off to a terrible start at the plate last season and rebounded fairly well posting an OPS of .650 over the last 4 months. An OPS of around that level plus the value he brings defensively is likely more value than Mercer can provide. The best case for Mercer is that both players will likely bring similar value but the highest upside is with Mercer. Not only that but Mercer could have a future with the Pirates beyond this year whereas that seems highly unlikely for Barmes. Even if the affects of an upgrade are minimal seeing what we have in Mercer is in its own way beneficial.
In actuality there is likely to be little difference between the two so that would seem to imply a third option is needed to improve the team, using the two as a tandem is such an option. Using Mercer at short in games where offense would seem to be at the premium makes sense and using Barmes at shortstop in games where defense would seem to be the most important also makes sense. One could put a lot of factors into determining which games are which but in reality there is only one major factor that needs considered and that is the Pirates starting pitcher. On days when big strike out guys like Burnett and Liriano take the hill infield defense isn't as important and conversely when ground ball guys like Morton and Gomez take the mound infield defense becomes immensely important. Tag teaming the shortstop with starting pitchers may seem odd but I believe it is the best way to get maximum value out of a weakest position in the lineup.