A 1-0 home defeat to Real Sociedad on Monday ensured Malaga remain just above the bottom three, with their advantage over Real Valladolid only three points.
A lapse in concentration allowed Carlos Vela to score the only goal after only 10 minutes and Schuster was left frustrated as his side were unable to recover from that early setback.
"We didn't do enough to win," he admitted. "We just couldn't overcome the rival's relatively slow pace on the pitch.
"We always react well when we're behind on the scoreboard, which is a good quality the team has always had, and will continue to do so.
"However, mistakes are costing us dearly, particularly in the situation we're in now."
Striker Roque Santa Cruz felt Malaga had done enough to earn a point, but rued a handful of missed chances that proved costly.
"I think we were unlucky, and the rival keeper was extremely fortunate to save a number of promising shots at goal," he said.
"We lacked a bit of confidence when it came to goal chances, but I think on the whole we performed well.
"I hope we learn from this game and start every match with more intensity."
Malaga have now lost their last two league matches, and face fellow strugglers Almeria and Valladolid in their next two Liga clashes.
