Colin Dunford and Seamus Prendergast bagged two goals apiece, with Brian O’Sullivan and Killian Fitzgerald also recording majors.
McGrath wasn’t reading too much into a facile win, though.
“We’re just glad to get up and running again after the club campaign. It was a blowout and nothing more. We’re just glad to get hurling again, the ground is drying up and looking forward to the game in two weeks. That’s what it’s all about.”
Dunford, Gavin O’Brien and Eddie Barrett were among those to make pressing championship claims.
“It has to be about that as regards to your panel. You are looking at all members of your panel at all stages. Different fellas are putting their hands up for the jersey,” added McGrath.
After an untidy first quarter, they outscored Offaly by 2-11 to 0-3.
O’Sullivan beat James Dempsey on 22 minutes and Dunford added a second goal on the half-hour. Dunford, a Croke Cup medallist with Dungarvan Colleges last year, ended on 2-2 for the evening.
A spate of changes followed for the Déise as McGrath used 27 squad members. .
Brian Whelahan looked at 23 players but the Faithful registered a measly six points from play. Only captain Joe Bergin caused brief disturbances on a relaxed evening for the home defence.
Kevin Moran started in the six slot with Michael Walsh at midfield but judgement will be reserved on that switch until another day.
Scorers for Waterford: C Dunford 2-2, S Prendergast 2-1, P Mahony 0-6 (4f, 1 65), G O’Brien 0-4, B O’Sullivan 1-1, K Fitzgerald 1-0, J Nagle (1f), S Walsh, E Barrett 0-2 each, J Dillon, T De Burca, A Gleeson 0-1 each.
Scorers for Offaly: J Bergin 0-6 (5f), B Carroll (2f), E Nolan (1f) 0-2 each, C Coughlan, S Dooley, C Slevin, K Connolly 0-1 each.
WATERFORD: S O’Keeffe; N Connors, L Lawlor, B Coughlan; J Nagle, K Moran, T De Burca; M Walsh, E Barrett; G O’Brien, P Mahony, A Gleeson; B O’Sullivan, S Walsh, C Dunford.
Subs: I O’Regan, J Dillon, S Prendergast, R Foley, P Prendergast, S McNulty, S Fives, S Roche, T Connors, S O’Sullivan, B O’Halloran, K Fitzgerald.
OFFALY: J Dempsey; N Wynne, G Healion, D Mooney; M Egan, D Morkan, C Parlon; K Connolly, S Ryan; Ciaran Slevin, S Dooley, P Geraghty; B Carroll, J Bergin, E Ryan.
Subs: Conor Slevin, C McDonald, S Óg Lyons, C Doughan, C Coughlan, T Geraghty, E Nolan, B Harding.
Referee: P Foley (Waterford)