dogging it

Yeah I'd think that underperforming would about cover it.

I think you'd have to add deliberately underperforming....because the nuance implies a sports player (for instance) is dogging it out of laziness and/or indifference...not out of a lack of ability. As in "not hustling." i.e If the fastest runner on the team takes his time and gets thrown out, then you'd say "man, he was really doggin' it." BTW, the USn idiom would seem to be dogging it...don't think I've ever heard dogging without the it.