NEW YORK ( TheStreet) -- Fund companies often lecture shareholders about the need to hold for the long term. All too often investors panic at market bottoms, dumping their shares at the worst possible time -- and missing stock rallies. That happened last year when funds faced a flood of redemptions.But retail investors aren't the only ones who make questionable moves at market bottoms. Fund companies recently fired several prominent managers, including David Dreman, former manager of the DWS Dreman High Return Fund ( KDHAX); Bill Miller who oversaw part of the Masters Select Equity Fund ( MSEFX); and Robert Turner of the Vanguard Growth Equity Fund ( VGEQX). Those managers had suffered periods of poor performance. But after they were fired, their investing styles came roaring back. Consider Dreman, who ran the fund from 1988 until he was replaced in June 2009. A diehard value investor, Dreman bought stocks at deep discounts. While the approach periodically suffered dry spells, Dreman always rebounded. In recent years, Dreman recorded big losses because he favored troubled financial businesses. Still, his fund had outdone 66% of his large-value competitors during the 15 years before he was sacked. The company changed the fund's name to DWS Strategic Value ( KDHAX), and replaced Dreman with managers who buy stocks that sell at moderate discounts. The strategy is bound to be less volatile than Dreman's deep-value method. But it's unclear if shareholders are well served by the change in portfolio managers. After Dreman was replaced, DWS Strategic Value returned 22% for the last six months of 2009. That was 5 percentage points less than a fund Dreman has continued to run, Dreman Contrarian Large Cap Value ( DRLRX).