With speculation that the Red Sox may end up breaking the bank for Mark Teixeira, it's time we discussed how valuable he really is.

Dave Cameron goes into this subject on Fangraphs.com. Estimating that Tex is a worth an additional five wins above a replacement-level player, he comes up with the following values:

If Teixeira is a +5 win player, and we use the $5.5 million per win projection for off-season spending, that gives us a $27.5 million figure for 2009. Again, we’ll factor in a 10% discount off of his current value for the safety of a long term deal, and that gives us something like $24.5 million for Teixeira. Teams are more comfortable giving longer deals to hitters than pitchers, so let’s pencil him in for a 7 year, $171 million contract.

Pretty incredible, huh? How many of us would have valued Tex so highly?

I have some issues with these figures. First, Cameron bases the offensive value of Tex (+3 wins) on the last two years. Why is that significant? Well...

OPS+
2003: 102
2004: 131
2005: 144
2006: 126
2007: 150
2008: 151

Over the last two years Tex has put up the best overall offensive numbers of his career. Ages 27-28 is when most players start to peak, and Tex is now 28. It's not wholly unreasonable to project Tex based on his age 27 and 28 seasons, but we should keep in mind that he's had less spectacular seasons as recently as two years ago.

Another issue is that Cameron does not plan for any age-related decline in Tex's performance. Most players begin to decline offensively after age 32. A 7-year deal would pay Tex to age 35. It's a little optimistic, to say the least, to expect Tex to 1) hit as well as he has in his career years, and 2) to hit that well over seven years.

Since we're talking Manny money here (>$20 million per year), how does Tex compare with Manny at age 28? Manny also had career  years at age 27 and 28 (OPS+ of 173 and 186, respectively), but he had been much more consistent, prior to that. His first season with more than 90 games (1994, age 22), he had a 125 OPS+. Thereafter he had four years of 144-147 OPS+.

For my money, Tex is a much more comparable hitter to Jason Bay. Their career OPS+s are very close - Tex is 134, Bay 131. Manny is a career 155 OPS+ hitter.

Turning to defense, no one would dispute that Tex plays a mean first base. However, so does Kevin Youkilis. According to the Fielding Bible's Plus/Minus, Youk edges Tex +25 to +22 over the past three years (2006-2008). Teixeira's defense is not worth as much to the Red Sox, who can keep Youk at first, as it is to the Yankees or Angels, both of whom have holes at the position.

I'd revise Teixeira's value downward, especially for the Red Sox. Since we receive no marginal gain in defense (and might even suffer by replacing Lowell with Youk), a fairer value for our team might be +3 wins, or $16.5 million a year. I'd throw some money on top for inflation, and offer a competitive rate of $18 million a year.

All this said, the best part about signing Tex would be hurting the Yankees and the Yankees West (LAA of A). New York faces the long-term prospect of a declining offense, as their stars age and their young players fail to hit (see "AAA" Melky and "No-Walk" Cano). Tex could help them, although he'd block Posada / A-Rod / Jeter from moving to first. The Angels, meanwhile, would have given up the promising Casey Kotchman for nothing more than a Red Sox draft pick. Moreover, they'd still be down a power hitter. In the end, Theo may decide that kneecapping our playoff competition might be worth overpaying for Teixeira.

So, to the big question: What do YOU think Teixeira is worth? Answer the poll, and leave your thoughts in the comments below.