Europe begin their defence of the title they retained at Medinah next week in Gleneagles, with both teams having finalised their teams earlier this month.
While McGinley's picks of Stephen Gallacher, Ian Poulter and Lee Westwood - at the expense of Luke Donald and Francesco Molinari - did not raise too many eyebrows, his counterpart Watson has been in the spotlight over his picks.
Keegan Bradley and Webb Simpson have struggled for form of late while there is no place for FedEx Cup winner Billy Horschel or runner-up Chris Kirk.
Despite question marks surrounding the American team, McGinley - a three-time Ryder Cup winner as a player - has warned his team will not take the United States lightly.
"There are questions and there is that kind of talk going on but to be honest I'm under no illusions and neither are the players," he said on Wednesday.
"We're all really gung-ho and ready for this Ryder Cup - this is not about being complacent.
"If we don't win this Ryder Cup it won't be because of complacency I can assure you. We're very motivated and we know it's going to be a very strong American team and a strongly led American team as well.
"This is not going to be a case of turning up and the Americans rolling over, it's going to be very difficult to win this Ryder Cup.
"It's going to be a slightly different threat from America than we've had in the past in so much that they really feel as though they're underdogs and up against it.
"The questioning and the form - that can galvanise a team. We've seen that in the past, certainly from a European perspective.
"Not being on form and question marks over the team, that can really galvanise - we will not be underestimating America, I can assure you that.
"We will be absolutely ready for this."
Those members of the European team involved in the latter stages of the FedEx Cup - Rory McIlroy, Justin Rose, Sergio Garcia and Martin Kaymer - are all resting ahead of next week's event at Gleneagles, while Jamie Donaldson, Lee Westwood, Stephen Gallacher and Thomas Bjorn are to feature in the Wales Open at Celtic Manor.
McGinley feels the differing approaches prior to the Ryder Cup will work out for respective players and hopes it will avoid the sort of form that meant Europe were required to come from 10-6 down on the final day at Medinah.
"When I got the job I was aware of the schedule and looking at what the week before was like - it's very important what the week before is like," he added.
"I'm delighted the guys in America have got a week off to prepare, because they need that and they didn't have that in Medinah.
"I think we suffered from that - suffered from fatigue.
"In terms of the guys playing this week, I wanted to align the setting of this course [at Celtic Manor] to [Gleneagles] in preparation for an examination at Gleneagles next week but in a competitive environment."