I'm an amateur Grammar N@z! so I'll help...I think.
Some comments:
Personally, I would delete "had" and changed the tense of the verbs that followed and revise the passive voice; "the kid at bat hit the ball, ran to first, but the first baseman tagged him out a split second..."
I think here, the long form (as opposed to the contraction) works better: "[i]n this line of work, you are your own team."
The rest of my comments are more about style than outright errors. It was enjoyable, and I could find myself in Jeremy's position.