Thanks for the advice and ideas! The hole was an irregular shape, and on the forearm, so I couldn't find a patch at the fabric store that would work. I ended up buying a remnant of a slightly stretchy, jersey-type material that was a great match for the predominant color in the jersey. The jersey has a very busy print. I took Beth's advice and stitched up the bits I could. There was still a big hole, so I sewed a little patch on the inside of the sleeve. It looks quite lovely, if I do say so myself. The materials were $5.13, and I have a bunch of the remnant left, so it was an inexpensive way to fix my $80 jersey.

Because the print is so busy, you can't even notice the blood stains from my altercation with the downed tree limbs.

Alex