Rovers were left stunned as Dwight Gayle plundered a 27 minute hat-trick giving the home side a mountain to climb.
To their credit Rovers rallied after the break, but goals from Jordan Rhodes and debutant David Jones weren't enough as they suffered a surprise defeat.
"I won't be able to put that first half performance to bed for the rest of the season," Appleton told Radio Rovers.
"It answered a few questions with certain people today. I think what happened today has been the problem over the previous five months.
"It is a division that you can grind results out if you are disciplined and organised and willing to put a shift in.
"There weren't players in that first half, that, for me, looked as if they were motivated to try and win a game of football. If the rules had allowed I'd have made six or seven changes at the break rather than the three I did make."
Whilst the disappointment rightly centred on the first half showing, the manager felt that the display in the second gave encouragement.
"It was chalk and cheese second half," added the manager. "Yes we gave them a couple of chances but that was only because we were so positive in throwing men forward.
"The chance that Lowey had, if that had gone in I would have backed us to go on and win it rather than just get a point. I think there was 12 or so minutes to go at that point.
"But it wasn't to be and now it is an opportunity for five or six players, including the lads that have come in, to show what they can do."