A few years ago I owned David Wright in my fantasy league. Wright did well in the HR derby and proceeded to hit 4 the rest of the year. The derby screwed up his swing, he did not seem to go to right the remainder of the year.
This year I own Morneau AND Hamilton. I’m looking to trade them both.
I guess it can happen, but I wouldn’t say that it is a foregone conclusion that they will do poorly after the Derby. As a Met fan I remember Wright doing very well in the Derby in 2006 and then going on to struggle with his power very badly in the second half of the season. However, Wright finished second in the Derby that year to Ryan Howard who, if I remember, did extremely well in the second half.
I think it may have had to do with the fact that Wright, although he has power and is certainly capable of hitting 35 HRs a season, is not a “power hitter”, whereas Howard is. Morneau, like Wright, can hit for power but is also not your typical power hitter, Hamilton is. I would hold on to Hamilton if I were you.