Nick Macleod and Johnny Leota touched down to go with eight points from the boot of Danny Cipriani for their first Aviva Premiership victory of the season.
It came just days after Diamond had taken over first team affairs with Bryan Redpath being demoted to head coach.
And the CEO was pleased with the team's response.
"The week's been different," he said.
"But the coaching team behind the scenes know what they're doing, the lads paid attention to what we've done in the week and we managed to get a hard-fought win tonight.
"We stuck to the game plan and we played well in the first half. We had a shaky start at the start of the second half where we gave the ball away six or seven times through handling errors."
Meanwhile, lock Richie Gray pulled out before the match and looks set to miss Scotland's opening game of the autumn internationals against New Zealand.
Despite his absence, Sale's set-piece was superb and Diamond praised the Sharks' pack.
"We've managed to get our scrum sorted out to a large extent and our lineout's effective," he added.
"Ross Harrison needs a special mention at 19 years of age as he was outstanding.
"There was also Tony Buckley, who's got a lot of critics but is coming on by the day. The problem we'll have is that Ireland will probably take him very soon."
Diamond's opposite number, Brian Smith, bemoaned the refereeing in the scrum and the lack of preparation time Irish had after they played Harlequins last Sunday.
He said: "We were on a five-day turnaround which is a little difficult, but we also had the added issue of the international players being unable to train this week.
"We were patched up, but fair play to Sale as they got hold of the game early. However, I thought we were a little unlucky with the scrum penalties in the first half.
"Certainly going into the game we had a dominant scrum. We struggled to understand that and the boys were a little frustrated.
"We lost our discipline and that cost us, but fair play to them, they scored twice against us and we fell off tackles against their power centres a couple of times.
"We believed we could peg them back so we made a tactical change to play with three locks in an attempt to try and squeeze them.
"At 15-9 we looked like we were going to turn things around, but at the end of the day we came away without even a bonus point so we've got egg on our face now."
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