The Sulphurites suffered their fourth defeat in six League Two matches when they went down 3-0 at Leyton Orient on Saturday, a result which sees them drop to 14th in the table.
This latest defeat means that Harrogate have taken only two points from the last 18 on offer, and led assistant boss Thirlwell to concede that too many players' standards have dropped in recent weeks.
But, he adamant that there is sufficient quality within the Town squad to turn things around, insisting that it is just a case of finding a way to put the ball in the back of the net.
"I don't want to get too downbeat with the lads because that group of players, the vast majority of them, have been colossal for us over a long period of time and we want them to get better and grow with us and be League Two players," said Thirlwell, standing in for Simon Weaver, who remains in Covid-19 isolation.
"But, at the minute, being honest, some of, or a lot of them, have fallen below the standards that we expect.
"We have a way of playing, we like to have possession of the ball. I think we're at our best when we have good possession and move the pitch together and get into good areas. We've got good players to deliver good ball, and we have got forwards who can get in the right positions and put the ball in the back of the net - we have.
"That's what we need to get better at. You just have to find a way. Sometimes we need to score a scruffy goal, the ball coming off someone's backside or the bridge of their nose. We just need a scruffy goal, maybe a scruffy win.
"It can't always be picture-perfect football and carving teams open. We need to do what teams have done to us, and have done today. One chance, one goal. Two chances, two goals. That's what we need to get better at."
Despite a bright start to proceedings, Harrogate fell behind on 18 minutes when Danny Johnson finished off an incisive counter-attack, running onto Connor Wilkinson's ball over the top and firing past James Belshaw.
Johnson's second of the afternoon was an exquisite volley from a narrow angle just after the half-hour-mark, and the O's forward would complete his hat-trick courtesy of a free header at a 73rd-minute corner.
"Let's be honest, today they [Orient] ran out worthy winners. I'm not disputing that," Thirlwell added.
"This was a game that we deserved to lose, but a game that I thought we started very well.
"I think that in the first half, between both boxes, we played some really good football, but it becomes irrelevant when we concede the goals we did and we have no cutting edge in the final third."
Leyton Orient: Vigoroux; Ling, Coulson, Happe, Widdowson; McAnuff (Dayton 78), Cisse, Kyprianou (Wright 87); Wilkinson (Dennis 82), Johnson, Brophy (Maguire-Drew 82). Unused substitutes: Sargeant, Thomas, Akinola.
Harrogate Town: Belshaw; Fallowfield, Lawlor (Burrell 46), Hall, Jones; Thomson, Falkingham, Kerry (Kirby 60); Kiernan (Walker 84), Martin (Stead 60), Muldoon. Unused substitutes: Cracknell, Lokko.
Referee: N Hair (Cambridgeshire).