The visitors survived a Argyle onslaught and left Home Park with a 1-0 victory secured early on through Matt McClure in their only meaningful attack of the game.
Plymouth made all the running, with Nick Chadwick, Robbie Williams, Paris Cowan-Hall and Conor Hourihane all coming close to making a first-half breakthrough.
It was much more of the same after the interval, with Cowan-Hall hitting the bar and both Chadwick and Darren Purse heading narrowly wide to frustrate Fletcher.
"We dominated about 90% of the game," he said. "Wycombe had one chance and scored, and we didn't score. That was about it.
"In everything apart from the final third, we were really good - the lads' effort and work-rate was great - but we didn't put the ball in the back of the net.
"That was the difference in the whole game. We dominated from start to finish but couldn't get that goal. We lacked a bit of quality in the final third, the make-or-break area.
"On performances, we shouldn't be anywhere near where we are but you deal with the situation that's thrown at you.
"It's obviously disappointing not to get a result because we've been on a good run and should have got a lot more."