The Great weakness in the Imperial war machine.
The empire is a massive, powerful war machine that has ties to the great Army of the Republic. And yet, for all of it's mighty ships, sheer firepower, and captains, there are the signs of a potential catastrophic problem. For in spite of it's predecessor's vast fighter corp whom among other things played a vital role in defending republic ships from the Seperatist fighter swarms, any expert whom studied the on paper statistics of the various Empire craft would notice one glaring discrepancy. Namely the number of TIE fighters would nearly always fall short of the projected numbers for a ship, which is especially problematic considering they are meant to protect said ships from bomber attacks.
While the Empire enjoys having no real peer and being in possession of every known starfighter factory, should one of our enemies manage to acquire a bluprint for a fighter with similar overall quality as our TIEs and the means to build them, said enemy could very easily escalate to a potentially catastrophic threat. As while on paper we should be able to handle such, the problem is the ship design teams didn't really design most of our ships to be able to fend off any serious fighter attack without a full TIE compliment, which is a very rare sight in the navy thanks to the fact that the only serious fighter threat nowadays is mostly the likewise lacking compliment of fellow moths and UGLIES whom can't compare to the TIEs the Empire fields.
While in theory it would be an easy fix, in practise it is anything but, thanks to the real problems that this is only a symptom of, it is far more difficult and complicated. For, well, the tarkin doctrine which emphasizes intimidation, when paired with the prestigious nature of commanding ISDs and the cutthroat nature of politics, ensure there is an endless demand for more ISDs and bigger ships, while undervaluing the humble corvettes and fighters. And to only further exacerbate things, in spite of the absolutely critical role, short of a rare few aces, they are often treated as nothing more than cannon fodder, to be tossed at the enemy carelessly, with the perception even bleeding into the training somewhat. These two factors are the true core of the problem, and one that will need solved if there is any real effort to fix the glaring weakness in the grand war machine. But of course, it is unlikely any effort would be made to actually fix this issue until the Empire is forced to accept it by an enemy equipped and ready to punish the empire for it's self-made weakness, and even then, it is difficult to say if those with the awareness to see the problem for what it is would be able to actually force the change through thanks to how deeply engrained big ships are in politics.
A/N: Well, decided to write something of a short essay thing, of essentially an analyst that for one reason or another saw the major flaw in the empire war machine.