The structure of fantasy baseball often leads to irrational instances of player loyalty. You spend your off-season researching players for your draft in March, and then you spend the season watching these players regardless of whether they are on your favorite team or just one of the guys you follow on your fantasy roster. It only makes sense that you can grow some sense of attachment to these players once you have drafted them because some amount of research—whether it be your own work or information you read here at Baseball Prospectus—indicated that the player would succeed, making tough to give up on the projections you had for one of your players. The truth is, though, stuff happens, and things rarely work out as planned.

Nobody could have predicted Casey Kotchman would be contending for the American League batting title this season after hitting .217 last season with Seattle or that he would be more productive than Adrian Gonzalez has been over the last month of play. Lance Berkman looked like he had one foot in the retirement bucket last season while splitting time between Houston and New York, and now he is a strong MVP candidate in the National League as he is putting up numbers like he did six seasons ago in his prime. Ryan Vogelsong has eight wins and the third best ERA in all of baseball right now, and Ryan Dempster has posted his worst ERA since the 2003 season. Dempster may have cost the most money on draft day, but Berkman was cheap, and Kotchman and Vogelsong were likely only drafted in 40 team mixed leagues with 50 man rosters.

Hopefully by now, you have given up hope on some players that are killing fantasy rosters all across this fine passion of ours. Offense is down all over the league, but there are certain players that have been mired in miserable slumps this season that have done the lion’s share of dragging down overall numbers as well as fantasy teams this season. Here are four players that are guilty of this, and hopefully you have already moved on or changed your outlook on these players that are clearly not getting it done in 2011.

Matt Diaz: Diaz hit 20 home runs in his previous 669 plate appearances heading into 2011, most of which came in his career season of 2009 and last season in a platoon role.  Yet, he entered play on July 26th still in search of his first home run of the season. He has 176 at-bats this season and has 11 doubles (and even a triple) but has yet to hit a ball out of the park.

Chase Headley: Headley hit 12 home runs in 2009 and 11 last season but has knocked just three out of the park in 2011. He went from April 3rd to June 8th without a home run—a stretch of 194 at-bats. While third base has not exactly been a fantasy gold mine this season, Headley has still been a major disappointment in the home run department.  He as nearly matched his doubles total from last year, but that is not a scoring category for a lot of leagues, and Headley is on pace to also fall short in matching his runs, RBI, and stolen base production from last season.

Franklin Gutierrez: He hit 30 home runs over the past two seasons but came across a nasty intestinal virus this off-season that has clearly affected him this season. He is hitting just .194/.231/.231 on the year and has not hit a home run since May 26th. Since his home run on that date, he has but three extra base hits and six runs driven in over 165 plate appearances.  Gutierrez is also suffering from another bout of lack-of-production embarrassment as he has gone 24 games and 80 at-bats since his last RBI.

Joe Mauer’s bilateral leg weakness has ruined his season, along with the hopes of winning a league for anyone who drafted him. I spent $23 on him in AL Tout Wars and am still in fourth place overall, but I am left wondering where I might be if he was not still chasing his first home run of the season 158 at-bats into it. His on base percentage is 31 points higher than his slugging percentage this season, and he has as many walks (15) as he does runs driven in this season.

With these four, it is more than just a slump at this point; it is an epidemic. Yet, there are other players out there that have gone through similar slumps that are still having good-to-excellent seasons. Brandon Phillips went from May 15th to June 26th without hitting a home run but is on pace to exceed his production from last season.  Aramis Ramirez went from April 8th to May 29th without a home run—a 154 at bat span—but has been red hot since and has a .299/.342/.515 slash line on the season for an otherwise disappointing Cubs team.  Currently, Victor Martinez is 142 at-bats deep into a homerless drought that began on June 11th, but he has hit .345/.386/.401 during that stretch. The home runs have stopped, but he has eight doubles and 24 runs driven in over that period.

If we could identify when these players would go into slumps and when they could come out of it, it would take all of the fun out of fantasy baseball. Why does Aramis Ramirez open up the season with a gigantic power slump and bounce of it with a vengeance while Joe Mauer still cannot buy a home run? This is where track records come into play as Ramirez has not hit fewer than 25 home runs in a full season of play since 2002 while Mauer has hit double digits home runs in just two of the last six seasons. As baseball fans, we’re taught to give stats enough of a sample size before we rely too heavily on them, but as fantasy baseball fans, our competitive nature does not always allow us the luxury of waiting out slumps such as the one Ramirez went through or the one Mauer is still in.

If anything, the struggles that Mauer, Gutierrez, and Headley are having this year should present draft day discounts in 2012. Mauer has consistently gone for $20+ in auctions and was even sneaking into the first round in many snake drafts this season, but I would be stunned if even the most diehard Twins fans were willing to take that risk next season. Maybe he can become the 2012 version of Lance Berkman, who disappointed so many one season only to reward so many others in the following one.