I see this question asked so often on the fantasy player message boards of such hitters as Ryan Howard, Mark Reynolds, Adam Dunn, Justin Upton, Adam Lind, etc. "Why penalize a batter's strikeouts?" I've heard several mediocre-at-best arguments supporting both sides of this discussion (ranging from "because it's one more facet of control the owner possesses," to, "because we reward pitchers' strikeouts the same amount and they should offset," up to the ridiculous, "there's no difference between a fly ball out, a ground ball out, and a strikeout; an out is an out." Let me refute the most inane of these claims and draw some easy-to-see parallels to other examples. Hopefully in doing so, I will have provided enough fact and insight in order to address why the fantasy reward for a pitcher's strikeout should have a different absolute value than the penalty assessed for a strikeout by the batter.
Most importantly, there actually does exist a difference between a line drive out (LO), a fly ball out (FO), a ground ball out (GO), and a strikeout (KO), from a purely out standpoint. Let us first examine the difference of a typical sequence of events for each outcome of a non-walk, non-HBP, non-line drive*, non-2 out** AB for a hitter, and I will use math in order to help assess the usefulness of these outs.
When a ball is put into play, runners whom are already on base assess whether the result is a ground ball or fly ball, and react accordingly. If a runner is on third base and the infield is not in, he will be running on contact in the event of a ground ball and trying to tag up in the even of a fly. With-runner-on-third ABs are the most productive outs because the geometry of the baseball diamond allows the runner coming home to run in a direction away from the ball and never towards it, thus increasing the amount of time the ball spends in the air and by transference, the amount of time the runner has in order to reach the next base, and also provides an RBI for each runner that successfully advances (barring a forced double-play with one-out already recorded, of course). If a runner is on second base, he will not automatically be advancing on contact, but again will use geometry to figure out whether to advance: a ground ball or deep fly ball hit to the right side of the playing field will again allow the runner to be running directly away from the direction from which the ball is thrown, thus increasing the likelihood that a runner will be able to advance a base, even on an out. If a runner is on first base, he will be forced to run in the event of a ground ball, but that doesn't mean geometry still can't help the hapless Hermes if the grounder is struck between the first baseman and second baseman: in this case the runner still has a good chance of moving to second; however, the chances of advancing on a fly ball are almost nil.
I point to the traditional average Batting Average - which I will forwardly refer to as ABA - of the non-walk & non-HBP possible outcomes of the AB for a player:
ABA(Line Drive) > ABA(Ground Ball) > ABA(Fly Ball) > ABA(KO)***
of course, with the ABA(KO) being equal to a goose-egg laden 0.00. So now we know that no matter where runners on base are stationed, a strikeout is not only the least likely of plate appearances to produce a hit but also that it will zero percent of the time be put into play, thus giving it a zero percent chance of advancing a runner and / or getting an RBI. This makes the KO the only guaranteed unproductive out for a hitter in baseball. It makes me wonder why those who complain about the penalties imposed on high power / high strikeout players chose to draft or acquire these players in the first place?
With so much of a baseball story being in the details, the world described by fantasy baseball leagues tends to both reward and penalize the acts that are guaranteed (both the good and the bad, respectfully), which is why batters strikeouts have come to be penalized. However, why should strikeouts be rewarded more heavily to pitchers (+1 in standard H2H leagues) than penalized for batters (-0.5 in those same leagues)? Again, probabilities and geometry tell the story. The probability that a batter will have an unproductive at-bat when he does not strike out lies in the direction in which the ball leaves the bat, or the trajectory. From an overhead view, if the ball leaves the bat to the left side of the second base bag, he is more likely to have an unproductive at-bat because the situations when a runner can advance on a ball played to the left side of the field are fewer than situations when a runner can advance on a ball played to the right. Conversely, a pitcher that can induce an out without requiring the ball to be put into play has the distinct advantage of depressing their ERAs, especially in situations with RISP. That is why pitchers deserve more of a reward for strikeouts than batters deserve to be dinged for the same act.
*Line drive outs are specifically ignored in the body of the text because the BABIP produced by line drives is so overwhelmingly high when compared to the BABIP produced by Fly Balls and Ground Balls that it would disrupt the flow of the argument; however:
When a ball is rocketed off of the hitter's bat, baserunners typically go in motion looking to advance to the next base at least. The reason for this is two-fold: 1. the high BABIP produced by line drives gives reason for the runners to believe that they should be trying to gain as much ground on the basepaths as possible, especially for runners stationed on first base; 2. because the ball is hit so hard, traditional though is that (barring a HR result), a line drive will reach a defending player sooner rather than later, giving the defender the opportunity to make a play on the ball sooner. The result of a line drive thus produces a high percentage of hits per line drive, and a high percentage of runners advancing on line drives hit, with only a small percentage of outs produced and additional outs produced per line drive hit. It should be fairly obvious to the lay baseball fan why producing a line drive means that the hitter had a good at-bat.
**Only non-2 out at-bats are addressed because there is almost always no difference in productivity to the type of third out produced in an inning, with maybe the rare exception being thrown out while trying to extend a hit by an extra base.
***where ABA(Line Drive), ABA(Ground Ball), and ABA(Fly Ball) are commonly referred to as BABIP of their respective delineations; however, BABIP is an inappropriate statistic to point to because a strikeout does not result in a "Ball In Play"