The Sharks conceded four tries at Sixways Stadium as they were outclassed 32-14 by the Aviva Premiership champions.
"We showed great spirit throughout but our skill set and application let us down at times on one-on-one tackles and then there is a mix-up in midfield just after half time which really nailed us," Diamond told Sky Sports News.
"But the spirit was good and we came across a side which are on the up. I've no complaints.
"We have got bigger fish to fry over the next weeks but we came here to give it our best shot and we are pleased with the effort."
Sale continue their fight against relegation from the Aviva Premiership on Friday when they host Bath.