So, according to ESPN, Luis Gonzalez just got extended for three years for a total of $30 million. There's a mutual option for a fourth year which is almost certain to not end up exercised by Arizona.

Gonzalez was a good hitter last year, hitting 288/404/496, which is essentially in line with his 2000 and 1999 seasons in Arizona. Yes, that 2001 was an aberration.

The guy is going to be 35 this year, though, and he'll be playing at 38 in the last year of this new contract. Interestingly enough, PECOTA figures that he's still going to be a valuable hitter at the end of this contract, though he should lose about three quarters of the value had last season by that point.
Since PECOTA projects his EqA to stay fairly high, it looks like it figures on greatly reduced playing time. (Note: I'm not going to post PECOTA figures here because of copyright. If you want to see 'em, you'll have to pay for 'em like the rest of us.)

Gonzalez is old, but he hasn't played less than 146 games since 1995, so he's been pretty durable through his lower thirties.

This also isn't just about performance, as Bob Brenly notes, "He is the face of the Diamondbacks." That wouldn't be an excuse if this were an atrocious contract, and while I don't know if it's a great gamble (the risk of giving guys contracts through their late 30's is exactly why I didn't want the A's to sign Jason Giambi), I don't think this is an atrocious contract, either.

Gonzalez is no Pat Meares, after all.