Player may be liked for on- or off-field reasons.
Player must be an average or below overall player. Neither Hall of Fame players, or players who would belong in the Hall of Very Good, need apply.
All periods are acceptable, and liking a player on the basis of a career year or short term burst of excellence is fine as long as they're predominately mediocre and they grade out as average or worse at their profession.
Just an example, I always had a soft spot in me for Aaron Sele. No particular reason, Sele was just the first rookie phenom pitcher I got to watch emerge. What he did that year was part of what got me hooked on baseball. Never turned into much, but he could eat some innings and make hitters look foolish on occasion. Made himself some money rattling around the league as a 200 inning mid 4's starter -- your bogstandard #3-4 guy, not bad, not great.
With that said, let's not rules-lawyer. I just picked a pitcher with a 101 career ERA+, I dun wanna hear about how a 101 ERA+ is not "average or below" or how he won a lot of games in front of great offenses OK?
So who's your favorite?