For the second consecutive Saturday their run-all-day centre-forward scored the winning goal. Mooney could be described as a bullish striker. He is not particularly subtle (although the delicacy of one second-half flick would have drawn gasps had it been executed by, say, Gianfranco Zola or Dennis Bergkamp), but he has a knack of scoring important goals.
To describe Saturday's result as an upset would be misleading, but as small clubs go Paul Jewell's Bradford are a lot bigger than Graham Taylor's Watford. At Anfield last week Watford's fans chanted that they were "by far the cheapest team the world has ever seen". Mooney, of course, cost pounds 100,000.
An advantage that Watford have at this early stage is that the squads of so many other clubs in the top division resemble the newly acquired furnishings of a Lottery winner's living room. There are lots of exclusive purchases sitting around, but their new owners still are not sure what to put where. Especially in the north-west.
Bradford are unsettled to the extent that they have three players who may be leaving the club - Robbie Blake, Darren Moore and Wayne Jacobs are reported to be departing this week in deals worth up to pounds 8m.
Bradford threatened in a single 20-minute period of the second half. Gareth Whalley found his range with a free-kick to the far-post and John Dreyer's header looped back over Chris Day before Mark Williams cleared off the line. Then it was the Tommy Mooney show. The utility player turned predator won an aerial challenge from a Micah Hyde delivery, dashed back into the box and headed firmly past Gary Walsh from Peter Kennedy's cross.
Jewell described the result as "a kick in the teeth". Ordinarily this might have been painful, but on Saturday his side had forgotten to put theirs in.
Goals: Mooney (71) 1-0.
Watford (4-4-2): Day; Lyttle, Page, Williams, Robinson; Hyde, Palmer, Easton, Kennedy; Mooney, Ngonge (Foley, 78). Substitutes not used: Walker (gk), Gibbs, Gudmundsson, Bonnot.
Bradford City (4-4-2): Walsh; Wetherall, Dryer, Jacobs, Halle; Lawrence (Saunders, 60), Redfearn (Grant, 72), Whalley, Beagrie; Mills, Windass. Substitutes not used: Clarke (gk), O'Brien, Myers.
Referee: R Harris (Risinghurst).
Bookings: Watford: Williams, Robinson. Bradford: Dryer, Jacobs.
Man of the match: Hyde.