Feehan said it should not be underestimated that Gatland's group became just the second Lions team in 13 visits to New Zealand to avoid a Test series defeat.
"I said all along that I think we had the best coaching team available and I think they proved that in what we achieved in New Zealand", Feehan responded through a statement.
"If we had a little more structure during the weeks, and more of an attack gameplan, driven way earlier in the tour, I think we could have won 3-0", BBC Sport quotes O'Brien as saying. "I think there's a lot of learning to take from the tour in terms of the coaching setup as well and from a player's point of view in terms how we dealt with things, but it's a weird one I suppose, drawing a series" he told Off The Ball.
Scotland head coach Gregor Townsend and Glasgow assistant Jason O'Halloran both turned down invitations to be part of Gatland's staff, and O'Brien - who also toured with the Lions in 2013 - says the best coaches must be recruited in four years' time. "That achievement can not be underestimated".
And he added that for the second Test, which the Lions won 24-21 to level the series, the direction for the backs came from influential playmakers Owen Farrell and Johnny Sexton, rather than Howley. O'Brien revealed to Irish site Sports Joe that after the test he found Kaino and said "you got me good". I was surprised and disappointed when I saw what Sean had said because it was a tour when everyone stuck together and showed great character to come back against a side that has been at the top of the world rankings for a very long time.
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"Unfortunately some people have focused on what I feel we could have done better instead of what we did well".
Ireland and Leinster flanker O'Brien took aim at the approach of the Lions set-up, led by Gatland, during their summer tour of New Zealand.
O'Brien, who played all three matches, said a triple training session ahead of the first test and a similar schedule before the decider had ruined the Lions' chances of victory.
"Coaching-wise they need to make sure they have the best coaches in the best positions - attack, defence, forwards, whatever it may be on a Lions tour", he said. "For me to sit here and say the Lions would have probably won is wrong". Maybe less is more sometimes on a tour like that.