Graham took his tally for the season to 25, first heading Watford in front within three minutes and then drilling in a second just after the hour mark, leaving Don Cowie to round off a comprehensive victory in stoppage time.
Mackay said: 'Danny is more than a quality finisher or a poacher. He is a proper centre- forward, an all-round team player capable of working the opposition back four all on his own.
Fine form: Danny Graham (right)celebrates his 25th goal of theseason for Watford
'I am always getting asked about the play-offs but we are only one of 12 teams who could finish in there.'
Ipswich slumped to a third successive home defeat and have won just once in their last seven outings.
Manager Paul Jewell said: 'I hate getting beaten and to lose 3-0 at home is horrible. We gave goals away for fun.
'We don't seem to have anybody who wants to get on the end ofcrosses into the box and we're not ruthless enough. We've got a lot todo to get to where we want to be.'
Graham's second came after he raced on to John Eustace's pass beforeshooting low past Marton Fulop. A Damien Delaney error was clinicallypunished by Cowie from 20 yards.
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