Who on the Cubs roster is going to give you that in LF this year?
Different type of approach. As shocking as this may sound, the cubs last year were a bit of a HR or nothing team. They were second in the NL in HRs with 172. They had 576 RBIs. Roughly 1 in 3 of their RBI's came via a HR(just counting the batter not players on base). If you compare that to the top 5 NL teams in RBIs you have STL(17%), COL(24%), CIN(23%), ATL(28%), and ARI(20%). So, it's not the HR's from Soriano I care about because honestly they really don't matter. It's RBIs that matter or more accurately runs created.
The way the cubs go from being a terrible offense to at best probably NL average is to increase their team batting average and OBP. I gave an example earlier that showed 34% of their plate appearances were by guys who were sub .290 OBP. Unsurprisingly the cubs were 14th in the NL with .300 team OBP. OBP directly correlates to runs. The top 5 teams in NL OBP were STL, CIN, LAD, COL, and ARI who were 1st, 3rd, 7th, 2nd, 5th respectively in runs. So, in order for the cubs to be "better" offensively they have to improve their .300 team OBP. NL average was .315 with tops being the cards at .332. The cubs team BA last year was .238.
The 2014 cubs may not have as much power but this is their triple slash line up
C - Castillo .269/.341/.407
1b - Rizzo .238/.324/.412
2b - Bonifacio .262/.322/.340
3b - No idea who ends up here but last year 3B hit .221/.314/.434
ss - Starlin Castro .283/.322/.404
lf - Junior Lake .284/.332/.428(albeit small sample size)
cf - Ryan Sweeney .278/.336/.385
rf - Nate Schierholtz .265/.314/.438 vs righties Ruggiano .256/.328/.506 vs lefties
My argument is that this sort of line up boosts the 2013 cubs OBP to some where in the neighborhood of .310-.315 if not higher. Sure some players will play worse than their career numbers but some likely will play better. .310 to .315 OBP would be around the Brewers(74 wins last year .311 OBP), San Diego(76 wins .308 OBP), Washington(86 wins .313) and Pittsburgh(94 wins .313 OBP).
In other words, the point is you don't replace Soriano's production with one guy. If the cubs get this sort of improvement in OBP from LF, 2B, and SS specifically, they are a better team. And while yes that is an "if," OBP is a little more consistent than say BA because players tend to walk at a similar rate year to year where as BA is semi-affected by BABIP.