It can't be a TV issue, the Directv receiver is doing the MPEG decoding, not the TV (unless he's got a RVU TV)
Since he didn't specifically say it was only ESPN, I wouldn't make that assumption. He may see it happen more on ESPN because fast action tends to make minor issues more noticeable than with other types of programming.
If it isn't happening on all channels, it could be a LNB issue, cable/connector issue, or trees getting blown by the wind that affect only channels on 99.
If there had been a transmission problem affecting ESPN for the past month, I would have seen it, as would others. I haven't seen any issues with ESPN - not on Directv nor my cable TV at home.
As for the course of action, I already recommended he call Directv again and a different CSR will probably give him a different answer. He needs to get someone out to check out his system (unless he's wanting to diagnose/fix it himself) If he's considering a Genie upgrade he can have the checkup done when they install it, and avoid having to pay for the visit.