Every signing is based on a range of possibilities, and Byrd's signing was a solid move on that basis.  Nothing about his later performance can change that -- nothing.  We haven't learned anything new that it was possible to know a year ago, when the decision was made, so our opinion of the decision itself should not change.

Unless, of course, "we" are children.

(By the way, ERA has its problems, but it's more relevant than batting average, and ERA alternatives are not as easy to come by and utilize as batting average alternatives.  Besides, I'm using ERA+, and I'm only using it to compare samples of 500-plus innings, both of which greatly reduce whatever shortcomings it has.)

Weaver is not a guy who is "in the midst of his prime" but has just "struggled recently."  (That actually sounds a lot more like Thomson.)  Weaver has been in a full-on sucky-to-average stretch for four years now -- and he was only decent-to-good for three years before that.  So, he's had more lame seasons than decent ones, and the lame ones were all more recent.  Are we really going to disagree about projecting this guy?

Weaver's three-month flirtation with "kind of good" was five years ago, and it now looks exactly like a slightly early peak or just a slighly flukey performance.  At the time, Weaver was young enough that he was expected to sustain and improve from that level -- he wasn't just "kind of good," he was "promising."  But as it turned out, that that was his peak.

The argument for Byrd is just this:  His 2005 season was better than any of Weaver's last five seasons -- significantly better, in fact.  And his 2004 season was basically the same, once he returned from rehab.  So what we're asking is, which is more likely:  Byrd (age 36) returns to his form from 1-2 years ago, or Weaver (age 30) returns to his form form 4-5 years ago?  And the answer is:  If I have to talk about this one more minute, I'm gonna barf.