Mulligan stages a comeback. (First Mutual Bank of Boston president Gerald T. Mulligan)

Hard-charging Gerald T. Mulligan has experienced the dizzying highs and lows of New England banking in the last decade like few of his peers.

As president of Boston's First Mutual Bank for Savings for six years and CEO for two more, Mulligan saw commercial real estate loans crashing all around him, bailing out of the institution just weeks before the Federal Deposit Insurance Corp. closed the $1.1 billion bank in June 1991.

Now, as CEO of high-flying Andover Bancorp, a thrift half the size of First Mutual, Mulligan has heard praise from the likes of investment guru Peter Lynch and a horde of Wall Street analysts as the bank's earnings have improved, its non-performing loans have been reduced and its stock has soared.

But just how much was Mulligan to blame for First Mutual's demise and how much credit does he deserve for Andover's ascent?

Local banking observers and industry insiders said Mulligan, who holds the same titles as he did at First Mutual, is a go-get-'em-type banker, a quality that can lead to extreme results, be they good or bad.

"I would say that the strategies that have been put in place at Andover, in terms of aggressively working their nonperforming assets, as well as building their investment portfolio of …