Stevenage boss Graham Westley rued his side's second-half performance in the 4-3 defeat to Oldham on Saturday.
Oldham were leading 3-1 heading into the final 20 minutes as first James Tarkowski cancelled out Darius Charles' opener for Stevenage and then Jose Baxter and Cristian Montano found the net.
Although Boro fought back and drew level at 3-3 thanks to goals from Greg Tansey and Filipe Morais, Baxter scored the winner from the spot.
"It's just been a really miserable day all round for us," said Westley. "We've put the effort in but that's not always enough at League One level.
"We were very much on top in the first half but you've got to try and kill teams off when you're in that situation.
"We got the goal at a great time, then in the second-half we just let them come at us and it can't work like that, it really can't.
"Oldham might not have been fancied to do particularly well in the league this season but we have seen from this match that they are going to be a real threat.
"They have brought some good quality in during the summer and they are going to upset a few teams. We have had a good chat and now it is about reacting positively. The games will come thick and fast now."