That meant City finished the season with 9 defeats from their last 10 games - including the FA Cup defeat by West Ham - and ended up 15th in the Premiership.
"I've got a lot to do this summer, we have lost too many games like this," said Pearce. "We need to bring in the right players and harness what we can in the current squad.
"Some of the big players we have relied on in recent years need to have a look at themselves. Of course, there will be pressure on me from the start of next season, but the club also needs leadership on the pitch.
"I know if I don't get it right I will lose my job. Finishing in the bottom half of the table is unacceptable."
An error by David James gifted Zuraw Khizanishvili a 35th-minute opener before Shefki Kuqi netted the second in the 53rd minute.
City were the better team before the opening goal but failed to score - even up against 10 men for the last half hour after Tugay was shown a straight red card - and Pearce was disappointed by the all-round display.
"The performance was very poor," he said. "The first half was symptomatic of the run we are on at the moment. They have not had a shot on goal and we have contrived to go in 1-0 down.
"With the confidence lacking as it is, it knocked our pipe out a little bit. There was something here for us today if we had kept our shape a little better. It's the nature of the game, 8 or 9 months ago we may have gone in a goal up, but that happens when you are on bad runs.
"The boys need a break, from each other as much as anything," Pearce added. "And for myself I need to work hard in the summer. Every team has a bad run in the season but ours went on for too long."