With the way Ross Detwiler performed in 2012 the Nationals are not looking for a great starting pitcher or even a good one. What they are looking for is a back of the rotation starter who can give them innings and keep them in games. Anibal Sanchez has the overall numbers of that type of pitcher having pitched at least 195 innings the last three seasons, and his 3.75 ERA is more of a mid rotation number than a back of a rotation number. The overall numbers of Anibal Sanchez don't tell the full story of Anibal Sanchez.
Sanchez is a pitcher capable of throwing a no-hitter. One who can look completely dominant, but he is also a pitcher that can completely blow up. Replacing Edwin Jackson with Anibal Sanchez is, in a way, replacing Edwin Jackson with a younger better version of Edwin Jackson, and the problem with the Nationals situation is that while they need a fifth starter there exist teams like the Royals and Orioles who may very well be willing to pay Anibal Sanchez like a top to mid rotation starter.
Sanchez has been worth 3.8 fWAR in two of the past three seasons and 4.4 in the other. Which averages out to 4.0 fWAR. Compare this to Edwin Jackson's 2012 WAR of 2.7 and the Nationals would be handing out a three or four year deal worth somewhere between $45-60 million for one extra win. The repercussions of a long term contract wouldn't be felt until the last year or so of the deal when his production and cost don't match and a better player like Meyer or Giolito are ready for the rotation. Even if the Nationals sign no one and put a 1.0 fWAR pitcher like Lannan out there that is better than overpaying for the likes of Sanchez and not having a spot in the rotation for when Meyer or Giolito are ready.
That is all looking ahead a bit and when it comes to pitching those types of things can take care of themselves through injury and poor performance, but the Nationals need a fifth starter and while Sanchez's overall numbers say he is that guy it is not at the price other teams will be willing to pay him, and when it comes to the numbers Sanchez suffers from the Monet effect. The closer one looks the worse the picture becomes.
Sanchez has the ability to be dominate. In all but two outings in which he pitched at least six innings he gave up three or fewer runs, and in the thirteen outings in which he pitched seven innings he allowed three or fewer runs in all of them and in nine of those he allowed two or fewer. The problem with Sanchez is that in the six outings he failed to complete six innings he allowed at least five runs. In all other outings he allowed five or greater runs twice. There is little middle ground with a pitcher like Anibal Sanchez.
Going back to 2011 it is much the same. In the 20 outings in which he went at least six innings he allowed three or fewer runs in 19 of them, but in the twelve in which he failed to go six he allowed five or greater in five of them. Compare that to Edwin Jackson in 2012. Jackson pitched six or more innings 18 times and in all but one of those allowed three or fewer runs, and when in the thirteen games Jackson failed to go six he allowed five or more runs in five of them.
Anibal Sanchez is better than Edwin Jackson, but he isn't better for the Nationals in their current situation and at what his contract demands are expected to be. If the market for Sanchez doesn't develop as expected, much as it played out for Jackson last off-season, then it could reach a point where it makes sense for the Nationals. Sanchez is a durable pitcher that will pitch to under a 4.00 ERA and those outings in which he is dominant are important. A team could do a lot worse as their fifth starter, but somewhere in the two year $22 million range makes far more sense for the Nationals than what teams more desperate for pitching are likely to pay.
There is a price where Sanchez makes sense for the Nationals, but the market will not have a chance to get there as a team like the Orioles or Royals would be smart to give Sanchez the money and the years he is looking for. Those teams that have a greater need for starting pitching than the Washington Nationals will be more willing to pay for the mid rotation starters than the Nationals will be. The Nationals do not lose much in throwing out a stop gap like Lannan for 2013 and waiting for the farm system to develop.