Good news on the door step? Part Two

Yesterday, John noted that the Washington Nationals signed Jason Werth to a seven-year, $126 million contract. That signing follows the loss of Adam Dunn, who enlisted with the Chicago White Sox for four years at $56 million. It is believed that Washington could have signed Dunn for less if it had moved earlier.
Is the signing of Werth good news? I think so. He’s an impressive player, and I shudder to think about a Nats line-up devoid of both Dunn and Werth.
Would the Nats have been better off signing Dunn and saving some money for other uses? Quite possibly. Werth and Dunn are actually similar in some important ways. First, they are both 31 years old. Second, their recent offensive statistics are comparable. In 2010, Werth slugged .532; Dunn slugged .536. Werth had a higher on-base percentage (.388 to .356), but in 2009 Dunn’s on-base percentage was better (.398 to .373).
There are some differences as well. The main ones are: (1) Werth is considered a good-defensive right-fielder, while Dunn is a considered a poor first-baseman and (2) Werth can run the bases and steal his share, while Dunn plods from station to station.
Another difference is that Werth bats right-handed and Dunn is a lefty. On the surface, this seems like an argument for Dunn in the context of the Nationals’ line-up, at least short-term. Dunn was our only power hitting left-hander last year, while we had several hard hitting right-handed batters. But Werth’s numbers against right-handed pitching were excellent last year — as good as Dunn’s, actually. And the Nats still have the opportunity to replace Dunn at first base with a decent left-handed bat.
The next difference between the two is that Dunn has been a hitting star for years (2004 was his break-out year, whereas Werth didn’t blossom until he reached Philadelphia in 2007 and didn’t attain his current level of production until 2009. There are several ways to look at this. The Nats reportedly think that Werth is only just beginning his peak years, but that would be abnormal for a 31 year-old. A better theory might be that Werth has thrived in the Phillies awesome line-up. Whether he will be as good in the Nats line-up, even in year one, remains to be seen.
On balance, I tend to think that the Nats would have been better off over the course of Werth’s contract with Dunn for four years plus the extra money, assuming they would spend it reasonably well.