User blog comment:B214/Chapter 482 review/@comment-25111584-20160418121237/@comment-25111584-20160418200617

If Dimaria stopped time, Ultear would help Jellal out. The Time Mage is not the Sky Bitches' sole property, y'know.

"The only reason Dimaria was hit was that she was caught off guard."

That means Dimaria has pathetic reaction time and awareness. Look at what happened when Dimaria tried the same trick on Kagura: she got blocked quite easily. If Wendy could do it even once Jellal, a vastly superior Mage and combatant, would have no problem catching Dimaria off-guard and then it would be curtains for her.

When not caught by surprise by the Sky Bitches' attacks, Dimaria could only defend. Exploiting openings during attacks to launch a counter-attack is quite basic. People like Natsu and Jellal wouldn't just defend, they'd use the opening to knock the kids senseless. Dimaria couldn't. Compared to Jellal, her physical capabilities are far too pathetic for her to be much of a challenge.