If the above quote is your evidence that "good connections to TPTB can outweigh rank and performance," then I respectfully say that that's entirely conjectural speculation on your part. The way I read that quote, all it says is that Decius may get someone to enact retribution on the commander for reducing him in rank. It doesn't say anything about said friends helping him to rise up in rank. And that's also speculation on your part, as there was no evidence whatsoever that Sela got her position because of her father's influence. All she said was that he was influential enough to save Tasha from death.