Jellal doesn't count because Erza was never serious in that fight. Jellal is the only person she will never fight seriously because she is head over heels into him.
Erza took a massive canon head on and destroyed the crying guy. She was barely standing at that point. If she had taken down a guild master in that condition I would have been raging YEARS AGO!
Besides that happened so long ago that it doesn't even matter now.
Just because Erza was established as strong character doesn't mean that she is invincible. Taison is a strong/one of the best boxer's but even he lost!
Besides as you all said Gildarts is stronger yet for some reason Erza never encountered an enemy of that level. They are never around unless Gildarts is there and to be honest even then such opponent appeared only once.
Natsu is an MC but even he lost far more.
What makes Erza worse is that she is always portrayed as a knight in shining armor. Everyone has their demons but never Erza. no matter where disaster happens she always has perfect timing and reaction. There is always something happening to make her look perfect. Natsu as an MC never got such treatment as she does and it only gets worse in manga.