Mike Pindelski at Beyond The Box Score offers an analysis of the still not completed Brian Roberts deal, pointing out that in Eric Patterson, the Cubs already have a second-base candidate with offensive potential...should the Cubs and O's be unable to agree on terms. He cites 5-year statistical projections for Patterson from Baseball Prospectus and summarizes things thusly:

"...Roberts would give the Cubs the most potent offense in the National League and he would surely give them the opportunity to make a run at the pennant in 2008.

If the Cubs however can't strike a deal for Roberts, there is no reason Cub fans should start throwing chairs. Assuming Hendry realizes what he has in Patterson the way he did with Geovany Soto, the Cubs have a pretty good in-house solution available for second base."

My counter-argument, which Pindelski mentions in passing:

By most accounts, E-Pat hasn't shown he can field the position.