Where was the Roman Army in AD408?

[Flavivs Aetivs]

It seems likely the desertion of the Gothic troops who had been mixed into the professional Roman regiments crippled the capacity of the Italic army (which about 6 years before numbered at least "30 regiments" and we know was still being updated in the Notitia as late as 419-428).

My guess is that it was understrength and morale was low, coupled with divided or uncertain leadership which made it as a whole ineffectual and logistically problematic to organize back into an effective exercitus.

We know Aetius had at least 2 significant field armies in 425-439 so it certainly wasn't gone.

Shortly after this Olympius is deposed and the 'troops in Ravenna' (Romans? Huns? 'Court guards'?) mutiny. So it seems that there were quite a few military units scattered about the place - so why was Honorius unable or unwilling to use them against Alaric? Was Alaric simply too strong to be opposed? Valens seems to have considered six thousand men from Dalmatia to be sufficient to confront the Goths (more fool him!)

Which proved to be not enough since those units (I believe it's stated its 6 Legions, is it not?) were annihilated and only like 100 men survived. He considered 6 Arithmoi totalling 4000 men from Constantinople to be enough to defend Ravenna, however.