Stevenage boss Graham Westley admits there is work to do if Boro are to challenge for promotion next season.
Westley was beaten for the first time since returning as manager on Saturday as Yeovil triumphed 2-0 at the Lamex Stadium.
James Hayter crashed the ball home from close range after 81 minutes to confirm all three points for the Glovers, who had taken the lead through Sam Foley eight minutes after half-time.
The visitors lost Dan Burn to a second yellow card in stoppage time but by then the game was all over.
For the home side, Dani Lopez had a 35th-minute header, which was destined for the top left-hand corner of the net, saved by a diving Marek Stech after the Spanish striker was picked out in the box by Lucas Akins.
It was the closest Stevenage came to breaching the Yeovil defence and Westley said: "In fairness there was a vast difference in the application of the two teams to win the game."
"There were too many moments where we didn't show enough discipline and organisation, we didn't show enough will to win, we didn't show enough urgency and that's why they are in fourth place and why we are where we are.
"We've watched promotion teams here. Promotion teams play a certain way. They keep the ball out of their net one way or the other. Their goalkeeper made a brilliant save. Whatever it takes you keep it out of your net and whatever it takes you put it in theirs.
"They had a bit more desire, a bit more care and a bit more urgency than we did and at the end they won. We tested ourselves against one of the better sides and we came up short in my opinion. We didn't come close to winning the points."
Westley masterminded successive promotions to League One during his first spell as Stevenage manager.