Ah, that explains it. But as soon as you leave your walls you're better off with pantodapoi or Caucasians on loose formation to divert HA fire. But the Pelt maks still puzzle me, they may be good against infantry and the best thing for you to choose when assaulting walls, but in the steppe they are largely useless - no spears, javelins don't do much against HAs(well they do if you hit them but they seldom come in range) just Hardy(not very hardy) and not as impenetrable as TAB.
For cavalry I'd suggest Lonchophoroi as they have the largest shield or when they field cataphracts: Aspidophoroi. Anyway there is nothing wrong with skythian riders, afterall the most usefull unit type in the open.

You could add 1-2 units of mercenary horse archers or generally invest more in archers as they eat numidians for breakfast. Afterall the Numidians will avoid the phalangites as they'd get slaughtered if they engage them^^