Sabrmetric stats on Wilkerson/Pierre in 2005 (stats from baseball prospectus)
.271 EQA, 74 EQR
502 AB, 386 outs made
7 BRAA, 0 FRAA (-2 FRAA at CF)
.253 EQA, 72 EQR
586 AB, 443 outs made
All statistics are park-adjusted, which means that they take into account that both players hit in pitcher's parks.
EQA is an attempt to summarize a player's complete offensive production in a single number. It takes into account just about everything a hitter can do offensively: hits, power, walks, HBP, sacrifices, SB, CS, etc. A .260 EQA is average; anything above .300 is all-star level. Anything above .330-.340 is a superstar.
BRAA is the number of runs above average a player is while hitting, and takes into account everything (hits, power, walks, HBP, SB, CS, etc).
FRAA is the number of runs above average a player is at his position defensively.
Dave, a number of studies have looked at trying to quantify how negative batter strikeouts are, and the end conclusion is that they're just not all that damaging - 100 strikeouts has the value of about -3 runs. As Tom pointed out, the negative of Ks is that they don't help advance runners - but the majority of all ABs come with the bases empty, in which case a K is no worse than any other kind of out. And when there are runners on, a K helps avoid a GIDP. In the end, a K is slightly worse than any other kind of out, but it's pretty insignificant. (example: 104 of Wilkerson's Ks came with the bases empty so far in 2005; he's got 33 Ks in 175 PAs with runners on. Pierre has 15 Ks in 206 PAs with runners on. The difference between the 2 is only ~18-19 Ks with runners on if you correct for playing time. And not all of those non-K outs advanced runners - a fielder's choice, or a groundout or flyball that doesn't advance the runner is no better than a K. in terms of GIDP, Wilkerson has 6; Pierre has 9. So Wilkerson's "extra" 100 Ks boils down to ~18-19 Ks with runners on, maybe 4-6 of which might have advanced a runner, but also 3 fewer GIDP. Looks pretty negligible to me)
And Pierre's SB totals are also pretty negligible - the break-even point for stealing bases is ~75% (ie, succeed less than 75% of the time and you hurt the team; break even at 75%, help the team if you're above 75%).
factoring in ks and SB, if you give each player 500 AB, Wilkerson will "create" about 74 runs for his team, while Pierre will create 61 (based on 2005 statistics). That's a substantial difference.