Ireland and Leicester flanker O'Brien took aim at the approach of the back-room team, led by Gatland, during their summer tour.
Spencer said: "This is the first time either during or since the tour that I have heard a player say anything like that".
"Not to be negative about it, it was a great tour but with the squad we had, we probably should have beat them". He is that good.
"So I don't know if it was people were not buying into what (Howley) was about or whatever else. Eddie has changed our mindset at England from always accepting we can't always be too outspoken and confident and he's really helped us a team to kick on". From in depth interviews with some of Irish rugby's biggest stars to unmatched insights into the provinces and the national team, The Left Wing has all your rugby needs covered.
Yes. Do I believe the Lions squad in 2021 will be better for this? Yes.
"Other times, he lets Dan Biggar for example and Rhys Webb have a huge say in terms of running the week because at global level you only have them for blocks during the course of the year".
"We did almost a similar thing in the last week.
Against all the odds and with limited preparation time, this squad became only the second Lions team in history to either win or draw a series in New Zealand in 13 attempts". That achievement can not be overstated'.
'Do I believe the players and coaches could have done better? Yes.
But the Leinster flanker has since claimed the Lions were overworked by coach Warren Gatland and his staff in the lead-up to at least one Test, while also suggesting the travelling team had the talent at their disposal to win the series 3-0.
"I think the first week we definitely over-trained on the Thursday - maybe the coaches were maybe panicking a little bit about getting the information into us and the workload".
The Lions were widely praised after the series against the world champions, having responded to losing the first Test by winning the second and then securing a gutsy draw in the third.
Speaking immediately after the drawn third Test in July, Gatland said: "Given the schedule, given how tough the tour was, to come to New Zealand and get a draw you've got to be proud of that".