Question about errors

I hope someone can help.

How does a ....Single (LF) (on the pitcher's card)

turn into a....... Single & Error LF 2-H 1-3 b-2

I'm perplexed by this. The LF is Willie Mays 1 (-5) e7

Please do tell if you know. Also, please pardon my ignorance.

My guess is a throwing error. But how are they determined? I'm lost. And a two base (for every runner) throwing error? Did he throw it into the parking lot?

Batter hits a single with runners on 1st and 2nd. The runner on second tries (perhaps unadvisedly) to score on the say-hey kid and one of those 7 Mays errors on the season comes into play with a wild throw. This allows the runner on first to get to third and the batter to advance to second.

Thank you, Sir.

Might you know where I can find the rules for how a throwing error is determined?

These rules are special and only apply on the computer game (pc or SOM on-line). SOM has not revealed how these errors are worked out, but my understanding is that SOM has compensated this introduction of throwing errors by reducing the probablity of making "catching errors" (direct E2 coming from the X-chart). The net result is that a player with a large E rating hurts less in the computer game than in face-to-face.

thank you both for taking the time to answer. And again, please pardon my ignorance.