Nationals must sign Kyle Lohse

An examination of advanced metrics explains why Kyle Lohse is still on the market. Jeff Curry/Getty Images

Fans of the Washington Nationals have much to be excited about, because a team that already won 98 games last year looks like it could be geared to be even better in 2013. This year's edition won't have to worry about shutting down Stephen Strasburg, and they surprised many by adding Rafael Soriano to what was already a solid bullpen.

They can expect improved outfield performance given that Bryce Harper has a year of experience under his belt, Jayson Werth has returned from yet another injury -- don't forget, he was excellent (.312/.394/.441) in 52 starts after coming back last year -- and they've finally filled the leadoff/center field hole they've been trying to patch for years by trading for Denard Span.

GM Mike Rizzo capped off his busy offseason by adding Dan Haren to the rotation, retaining Adam LaRoche on the club's terms and rebuilding some farm depth by trading the somewhat overrated Mike Morse to Seattle.

All in all, it has been a very good winter for the Nationals, and they're the consensus pick to win the National League East, especially given the teardowns in Miami and New York, and the continued aging of the Phillies. But for a team that's truly built to win now, there's one more move they could and should make -- they need to be the club that swoops in to sign Kyle Lohse, the one big-ticket free agent remaining.