Walter Donovan’s arrival as CIO of Putnam Investments this month may be the final touch in a major overhaul of Putnam’s investment team since Power Financial Corp. of Canada acquired the troubled, Boston-based asset management firm in September 2007. The 46-year-old is one of several senior managers, including president and CEO Robert Reynolds, to join Putnam from Fidelity Investments, where Donovan was president of equity. He views the recession as an opportunity to improve sorry performance (Putnam’s assets have fallen by 75 percent, to $98.6 billion, since the end of 1999). “It’s a very strong market for stock pickers because there is a good amount of breadth in the market,” he says. “This is about simple blocking and tackling — one research report at a time, one company meeting at a time.”