How can you tell if a merger is being mismanaged? You will see several of these major problems and the costs that accompany them:

Bailing out by managers and executives is one of the first signals that a merger is being mismanaged.
Typically, some of the best talent is the first to go. And their leaving more than likely means that somebody in the top ranks of the company made a mistake. There was something someone did, or didn’t do, that helped produce the bailouts.
Parent company executives have to move fast and do the right things to keep the people who count. Too often, though, just the opposite happens. The acquiring firm drags its feet and does things clumsily.
Many factors contribute to the turnover statistics in mergers. People leave for myriad reasons—some that make sense, some that don’t. But the point is that many of these people are very valuable employees, and they could have been retained.

So what does the loss of talent cost a company? First, there are some tangible, easily identifiable expenses associated with replacing a key manager or executive such as placement/search fees, relocation costs, training costs, and the time invested in the selection process.
The intangible costs associated with losing a key person are harder to gauge, although they can easily represent an even more expensive proposition...