The home side turned an 11-9 half-time deficit into a runaway win, but Young had a few gripes about his team's performance.
"First half was pretty disappointing," he said. "Up front we failed to get any platform in the scrum and lineout.
"We were second best in most departments. In attack we failed to hold the ball for any length of period to build any pressure and momentum.
"Coming in at half-time, the dressing room wasn't a very happy place to be."
However, a second-half transformation produced two tries for wing Tom Varndell and one each for scrum-half Joe Simpson and replacement prop Zak Taulafo, while veteran Wales fly-half Stephen Jones ended his Wasps debut with a 23-point goalkicking haul.
"We had to step up in every department and we did," said Young.
"Second half we looked a completely different team. We were far more potent with the ball in hand, defensively we looked far stronger and the forwards stepped up. We looked a far more complete team.
"I thought we deserved to win but the bonus point probably flattered us.
"I don't think we were that much better than London Irish but fair play to the boys to keep playing right to the end."
The Wasps boss was delighted with the way the 34-year-old Jones, with 104 Wales caps, combined with scrum-half Joe Simpson - capped once by England - in their first game together.
"Stephen brings the experience and a calm head and everybody knows Joe's a real threat in open play," said Young.
"Today I thought his defensive capabilities were excellent.
"His organisation with Stephen was good. They steered the ship really well."
Jones kicked five penalties and four conversions and Young added: "They weren't easy kicks but that puts a lot more pressure on the opposition."
Brian Smith, the London Irish director of rugby, has now seen his side concede 123 points in their opening three matches but remains optimistic they can quickly turn their form around.
He said: "There's no reason to panic. It's early doors in this competition.
"We went in with our tails in front at half-time but we dropped off the pace 55 minutes into the game. That's really disappointing.
"But we have to cop it on the chin. We have to take our medicine, learn our lessons from this defeat and soldier on."
Smith added: "We have a young group and we've struggled to put a win together. Young lads are only human and that's a problem for us but they're giving it all they've got.
"We were in the game up to the 55th minute. Now we have to learn our lessons and play for the full 80."
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