Rickie Weeks is slugging like crazy thus far, but I noticed that it is taking away from some of his other OBP skills -- such as walking (he is walking less than 4% of his PA, down from 12% of the time in 2008), and pitches seen (he is seeing 3.66 NP/PA thus far, down from 4.14 NP/PA in 2008). By extension -- perhaps because he is simply on base less -- he is also running much less frequently. In 2008, Weeks attempted to steal against 13% of his times on base (H+BB+HBP); thus far in 2009 he is only attempting to steal against 8% of his times on base.

This is all leading to less runs productivity. And this is not some "OBP is superior" rant. The whole point is that OBP indicates a certain set of skills, especially with a player like Weeks, who usually does secondary things very well. Now Weeks is doing a lot of primary things very well (AVG, SLG, XBH%, for instance), but he has not clicked with the things that made him a valuable lead off man with the Brewers the last two years. 

Here's a simple example, using runs created, of the cut-off / breaking point between OBP / SLG (assuming 0 SB, GIDP, SF, etc., for now):

600 PA, 210 times on base, 535 AB; 145 H, 60 BB, 5 HBP; 28 2B, 5 3B, 18 HR; 237 TB; .271/.350/.443; 88.9 RC

600 PA, 180 times on base, 565 AB; 145 H, 30 BB, 5 HBP; 35 2B, 3 3B, 35 HR; 291 TB; .257/.300/.515; 90.0 RC

Where a player gets on base approxiately 5% less frequently, that player will have to compensate with much more slugging -- by aproximately 7%.

In Weeks' case (assuming equal GDP, SB, etc.)

2008 (actual): 560 PA, 191 times on base, 475 AB; 111 H, 66 BB, 14 HBP; 22 2B, 7 3B, 14 HR; 189 TB; 19/24 SB; 1 SH, 4 SF, 5 GDP; 72.2 Runs Created

2009 (projected): 560 PA, 175 times on base, 519 AB; 134 H, 21 BB, 20 HBP; 20 2B, 0 3B, 27 HR; 235 TB; 19/24 SB; 1 SH, 4 SF, 5 GDP; 76.3 Runs Created

2009 (w/actual SB ratios): 560 PA, 175 times on base, 519 AB; 134 H, 21 BB, 20 HBP; 20 2B, 0 3B, 27 HR; 235 TB; 7/13 SB; 0 SH, 0 SF, 7 GDP; 72.1 Runs Created

Thus far, Weeks' productivity, overall, over 162 games, would be almost exactly similar to his 2008 runs production (against my initial suspicions); but yet, look at the importance that good, frequent baserunning brings to Weeks --  over the course of the season, that's probably worth just about a handful of runs.