What is up with sports fans?

At this point in the season, A-Rod is struggling. And the fans are booing him unmercilessly.
I don't get that. A-Rod is trying. It's not like he's not hustling, and working his ass off. And yet the fans boo.
I don't get it at all.
I used to work at a job with a boss that was an asshole. No other way to put it. Anything that I did that was not perfect, was subject to intense criticism. It was difficult to perform in that environment. The job was stressful because of the boss. Rather than instilling confidence, she made me doubt myself.
To me, A-Rod is in the same situation. His job is playing baseball. He is trying hard to do his best. Anything short of a homerun, his best, seems to elicit boos from the Yankee faithful. That is stupid. Sure, if he fails to run out a ground ball, scream your head off, but anything else, he should be encouraged.
Think about the outcomes:
A Superstar, having a great year, in a 3 game series, will average one (1) home run in the series, maybe three (3) rbi's, two (2) other hits, and will strike out once or twice. Maybe walk once, and will make 8 other outs. A superstar, going really well, will fail at least 2 out of 3 times.
It just doesn't make sense to "boo" one of our guys. Absolutely nothing positive can come out of it.
It takes a special person to stand in front of 50,000 people and hit a 90 mile per hour ball with movement.
I can guarantee that few of the jerks booing in the stands could hit the ball off a tee with the pressure of TV and all those people screaming.
Why make it harder for our guy? Save your boos for the Red Sox.