From a huge fan and avid reader of all news regarding Cubs, trust me that it will not be working with Larry Rothschild that will fix Zambrano. He is notoriously old school in that he will not encourage pitchers to alter their mechanics and has a reputation with baseball people and educated fans alike of doing absolutely nothing at all in general to fix pitcher's problems. Zambrano has succeeded in spite of Rothschild all these years while the Cubs have failed to develop any other pitchers of note (besides maybe R Hill).
More than likely, Zambrano is struggling to keep his emotions in check (as always), pitching nervously due to contract pressure, and has even been stung by poor relief efforts by the Cubby bullpen/defense. Three extra earned runs charged to him after Cotts gave up a slam to Pierzynski, earlier a run scored (earned) on a Soriano miff of a pop-up, and at least one other incident of relief pitching coming in with his runners on and walking in two runs in a row, both charged to Zambrano. His HR rate is unusually high, and I noticed that last year he seemed to be giving up more HRs than before, but this year it is out of hand. He does need to get his ball down much more often, like in the past.
I still think Big Z will be fine. Obviously he won't win the Cy Young as he predicted (unless he just goes Koufax on everyone), but he should be putting up good numbers soon once he settles down, the relief corps irons out the wrinkles, and the D shows up.