Harper/Strasburg: Who is more valuable?

It has been a nerve-wracking 48 hours or so for the Washington Nationals. First, Stephen Strasburg pitched through some forearm discomfort in Monday's loss to the Braves, but he felt fine in a bullpen session Wednesday and will make his scheduled start Saturday. Then came another loss to the Braves on Tuesday. Then Bryce Harper left Wednesday's game in the sixth inning after aggravating his left side, originally hurt slamming into the wall on Tuesday. Luckily, like Strasburg's injury, it doesn't appear serious and he's listed as day-to-day. "Hopefully," he told MLB.com, "I can come in tomorrow, feel like a million bucks and play."

The good news on Wednesday was that Jordan Zimmermann was dominant in a 2-0 victory over the Atlanta Braves, Washington's first in six games against Atlanta, allowing just two hits with no walks and eight strikeouts.

Still, with the Nationals muddling along at 14-14, the injury scares to their young franchise players raises the question: Who is more valuable to the team? Or, to put it another way, if either Harper or Strasburg suffered an injury that did sideline him for a lengthy period of time, which would hurt the team more?

We can start by using projected value for the 2013 season. FanGraphs runs updated ZiPS projections, and Harper's hot start has him now projected to a season line of .281/.366/.511 and 5.3 wins above replacement. If anything, that's probably conservative; we know that among the first aspects of a player's game to stabilize in a small sample size are his walk and strikeout rates, and Harper's rates so far are better than his projected rates, arguably a sign that he'll outperform that triple-slash line.

The ZiPS projection for Strasburg has him posting a 2.96 ERA over 158.1 innings, worth 3.9 WAR. Again, that's probably conservative, since we know if he's healthy he'll pitch more than 158 innings. Projected over 190 innings, we'd get 4.7 WAR. Based on this simple comparison, we'd say Harper is probably more valuable.

However, WAR assumes a generic replacement-level player and not who the Nationals actually have to fill in. In their case, backup outfielders Roger Bernadina and Tyler Moore could platoon in left field; neither has hit in limited playing time this year but performed well a season ago and would likely be better than replacement-level. On the other hand, there is no obvious candidate to replace Strasburg in the rotation. Craig Stammen made 38 starts in 2009 and 2010 but was ineffective (ERA over 5.00) and had a 4.75 ERA starting at Triple-A in 2011. The current rotation at Triple-A Syracuse has been pretty horrific; the best starter has been lefty Daniel Rosenbaum with a 1.14 ERA in four starts, but he has eight walks and just five strikeouts in 23.2 innings, numbers that indicate he'd get lit up in the majors. Veteran Chris Young has allowed 11 runs in two starts and Yunesky Maya has a 7.45 ERA.

So it's possible that Strasburg's replacement could end up performing below replacement level, as well as forcing the bullpen to pitch more innings, something WAR doesn't account for.

Does that make Strasburg more valuable? Not necessarily. For one thing, it's probably easier to acquire a decent pitcher on the trade market than it is a good position player, so that's always a route general manager Mike Rizzo could take. There's also the issue that the Nats' offense has been terrible so far, ranking 12th in the National League in runs scored. Adam LaRoche is hitting .129 and has a single hit in his past 35 at-bats, Danny Espinosa hasn't hit, Denard Span has a .314 slugging percentage, Ryan Zimmerman is on the disabled list and Jayson Werth has missed a couple games with a sore ankle. Where would the offense be without Harper, their 20-year-old star?

The Nationals are ninth in the NL in runs allowed and behind Strasburg they have Zimmermann, Gio Gonzalez and Ross Detwiler. Even with Gonzalez and Dan Haren struggling so far, it's still a rotation that can you win you games, and on paper the bullpen is deep and strong.

Anecdotal evidence also suggests -- in this era of declining offense -- that perhaps it's more difficult to replace a star position player. The Cardinals won the World Series in 2011 even though Adam Wainwright missed the entire season. What if Albert Pujols or Matt Holliday had gone down instead? The Giants won the NL West and the World Series last year even though Tim Lincecum was one of the worst starters in the league -- but missed the playoffs in 2011 when Buster Posey went down early in the season. That's not proof, but with the way Harper is hitting, with the way the offense already seems to revolve around him, and with the question marks with some of the other position players, I would say losing Harper would be the bigger blow.

Hey, didn't Babe Ruth eventually move to the outfield?