Over the last few day, word has leaked out of San Diego that the Padres will be willing to talk to teams that might be interested in Jake Peavy this winter. More importantly, since Peavy has a blanket no-trade clause, was his agent’s statements that Peavy would be willing to accept a trade to certain contenders in the National League, paving the way for real trade discussions to take place.

Peavy, the 2007 NL Cy Young winner, will certainly draw interest. Over the last few years, he’s established himself as one of the game’s best pitchers, and he’s got an All-Star track record despite being just 27 years of age. He’s also under contract through 2012 (with a team option for 2013), so he wouldn’t be a one year rental or require an extension, like most big name pitchers who become available before they hit free agency.

So, an ace entering his prime signed up for the next four (or five) years is on the market – everyone should be falling all over themselves to give up the farm for Peavy, right? Maybe not.

Despite his shiny 2.85 ERA, 2008 was pretty clearly the worst Peavy has pitched since 2003, which was his first full year in the majors and the year before he broke out into an established front line starter. Let’s take a closer look at his performances from 2004 to 2008, using the graphs available here.

The strikeout rate, which had held extremely steady from 2004-2007, showed a noticeable decline this year, dropping to 8.60 this year, down from his customary 9.50 range. A loss of a strikeout every game isn’t the end of the world in isolation, but when it’s combined with a simultaneous increase in walk rate and home run rate, like we see in the last two charts, it’s cause for concern. His FIP of 3.60 reflects the downgrade in his underlying skills, and shows that he pitched worse last year than he did in 2006, when his ERA was much higher. He was able to keep runs off the board by stranding a ton of runners (his 82.2% LOB% was second highest in baseball), but LOB% isn’t nearly the solid foundation to run prevention that striking batters out, limiting walks, and keeping the ball in the yard is.

Recently, the boys over at StatCorner.com unveiled tRA*, which is FIP with a whole lot of extra regressions on batted ball types and park adjustments and such, and gives a pretty good indicator of how well a pitcher actually pitched, stripping out a lot of the noise that gets included in a pitcher’s final results. Peavy’s tRA* for 2008 was 4.41, putting him just behind Aaron Cook and Paul Maholm among NL starters. Not exactly the kind of company you expect to see Peavy included with, eh?

Peavy simply wasn’t as good in 2008 as he was from 2004 to 2007. He was still a good pitcher, but he wasn’t the earlier versions of Peavy that we’d seen. He was worse in almost every meaningful category. And he spent a few weeks on the disabled list with elbow problems to boot. He returned from those and pitched well, so it’s unlikely that he’s already sustained a serious injury that will prevent him from pitching, but it’s another red flag in a season that raised several even without the health concerns.

Peavy’s contract calls for him to earn $9 million next year before a $52 million guaranteed extension kicks in for 2010-2012. Any team acquiring Peavy would be on the hook for at least $61 million over the next four years, and if the team option for 2013 was picked up, it would be $79 million over 5 years. Even in today’s marketplace, that’s frontline starter money. For the last four years leading up to this one, Peavy was certainly a frontline starter, but his 2008 performance has to raise questions over whether he will continue to pitch at that level going forward?

The Padres seem to believe that now is the time to sell high. If 2008 Peavy was a sign of things to come, they’re probably right, and potential suitors for Peavy might want to consider alternative options before giving up a ton of prospects for a guy with some real question marks.