I'm pretty sure he won't keep his current line up (especially the walks), but either way, he's been a major asset.  I just did a marcel weighting his current performance (2008=0.83, 2007=4.83, 2006=3.83, 2005=2.83).  He's a safe Marcel since he's played 3+ years here.  That increases him from about a 2.7 per 600 PA WAR to about 3 WAR, assuming +0 UZR, which very well may be too low, and +0 positional adjustment for being 3B. 

.3 WAR difference probably won't make or break us, but it means his hitting the 2nd half of last year was probably legit, and he's probably a better hitter than a lot of people have given credit for (we all knew it).  Also Adrian Beltre is probably under paid at this point!  If it's at all possible, we need to extend him NOW.  Boras won't let that happen, especially while he's hitting like he is.