Having veteran players like Keane on the mic is enormously powerful for EtH. Because Keane probably reinforces what they're hearing from the manager. After that game vs Brentford there was no escape for these players, so by the time they arrived that day to run that 13km I am sure they were happy to do it. I would be.
There were a couple takes that week that were comical, with media types acting like it was a mistake to make them run on a Sunday. But I am sure the players care what these veteran players think, I mean how could they not. And in a club like this you want to fit in and be talked about among the greats, or at the very least not be a guy they're singling out to criticize because your effort isn't there. So there was probably a lot more willingness to work their butts off and turn it around than people gave them credit for.