Word is that Greenberg went rogue too often. Anecdotal evidence seems to support this.
Sorry it came to that, but this is the guy that (allegedly) freelanced the last trip to Arkansas, delayed JD's contract renewal, and meddledin the Michael Young affair to the detrement of all. Ryan/JD, otoh, were through pursuing Lee & were ready to shop young earlier than later. Plus, Nolan stood up to his money guys, who expected Wash & JD both to be gone as soon as they took the reigns. So Nolan will not be arbitrarily pushed around by big buckage, not at the expense of his baseball instincts. But he does have his limits, & apparently Greenberg went over them.
The last thing we need is another Jerry Jones/Mark Cuban type, especially one who doesn't really control the purse strings. Greenberg was a delightfully convivial "face" of ownership, and darn it, too bad how he was always upsetting those poor, put-upon Yankees, but I do believe that his departure leaves the ownership/management group in better, more capable baseball hands now that a proven freelancer/probably ongoing distraction has left. For better coverage than a mere NYT article, here's where to begin: http://www.lonestarball.com/