Soriano underwent an MRI on Sunday night.
"He's not going to be out there any time soon," Cubs manager Lou Piniella said. "It's probably going to be a minimum of two weeks and probably as long as a month."
a month is more than half the remaining season, which is of course a serious problem for a team struggling to catch its division leader. the cubs have not been a great offensive club -- standing 8th in the nl in runs scored per game at 4.65 -- and particularly lacking in power, slugging just .410 as a team. soriano is the club's home run leader with 18 though he is also third in slugging at .511, behind aramis ramirez (.548) and derrek lee (.516), and is clearly the key cog he was intended to be when he was signed.
there seems little question that the loss of soriano damages an already problematic offense. to what effect is the question, and that remains to be seen. the club had plated just 4.25 runs per outing in the last 16 with a .308 babip and .378 slugging, backing off the torrid pace of the previous 23 during which they scored 5.39 a game on the solitary pillar of an unsustainable .332 babip aside a .408 slugging number. that spate of luck gone and further minus its leader in runs scored (74), the cub offense could be seriously impaired for the next few weeks without some good fortune. what little power it has is highly concentrated in a few players; the loss of any one of them could make a major impact.
something that's underrepresented in these discussions is the marginal difference that really separates winners from losers in baseball. adding up expected vorp or winshares of a team is one way to take the measure of a club, and it's clearly not without its virtues. but winning and losing is done at the margins -- that is, runs scored are most valuable to a club when they're the runs that put them over their runs allowed. that's a blindingly self-evident statement, perhaps -- that the tenth run of a 10-1 win doesn't mean as much as the fourth run of a 4-3 win -- but its ramifications are not always well represented in analyzing ballclubs.
soriano will be replaced in the lineup by some combination of matt murton and eric patterson, and that will represent some falloff in expected vorp. but the loss may be felt much more acutely for the cubs than it would be for a club that was either so good as to not miss those runs or so bad as to not benefit much from them. does soriano represent something like these marginal runs? maybe we're about to find out.
what it all means for the playoff hunt, however, will depend on the pitching as well as the offense. the cubs have benefitted all season from one of the best performing starting staffs in baseball. i've argued contentiously that much of that outperformance has been a fluke -- the product of unusually good luck on balls in play. indeed, i don't think the team has experienced the bad luck on balls in play which afflicts most teams at some point in a typical year over any significant stretch yet.
over the last 16, however, the cubs pitching staff has allowed a .313 babip against. it's translated into just 4.13 runs allowed per contest, but that may not hold -- and it may not be enough if the offense is both hampered by soriano's loss and not especially lucky.
we're left to guess somewhat as to what this club would really perform like with normal pitching luck on balls in play. i've looked at the 12-game babips in an effort to isolate the fleeting occurrences that we've seen this year so far.
when the pitching hasn't been lucky, the club generally hasn't played its best baseball, including just recently. neither is there perfect correlation, of course, between periods of bad luck and poor performance -- results in baseball depend on a lot more than pitching babip, after all, or even overall team babip differential (that is, offensive less defensive babip). the period of poor performance in games 69-80, for example, clearly had nothing to do with babip, wich was actually quite beneficial. (nor with slugging, as the club hit for more power than normal in that same run.) this is not an all-comprehensive model of the baseball universe.
but it should not be ignored that the club's low point this year came in the only period this season during which the club experienced a negative impact from babip, offensive and defensive, while also slugging quite poorly.
poor slugging figures to be a more probable feature without soriano, and with that a heightened sensitivity to variations in babip. if the cubs, for whatever reason, don't receive in his absence the benefits that babip has granted them most of the year to date -- in the first 45 games and then most particularly in july -- august could be a very disappointing month for a cubdom that expects first place.