A Self-Effacing Approach to Argument

I haven’t read any pieces by Plato in a couple of years; now that I have been assigned a few more of them to analyze, I'm beginning to notice that Socrates repeatedly employs a few rhetorical tricks which I either didn’t detect immediately or failed to remember.  Namely, he puts himself down quite a bit before posing questions or making statements.  

For example:

“I must grant it for your sake, since, because of my stupidity, I did not notice it.” (142)

“But, my dear Phaedrus, I shall make myself ridiculous if I, a mere amateur, try without preparation to speak on the same subject in competition with a master of his art.” (143)

It is obvious that Socrates knows exactly what he thinks of the speech written by Lysias, but he will not voice his criticisms until Phaedrus has repeatedly urged him to do so.  (Were I to speculate, I would suspect that Socrates planned on countering the argument at length all along, but for the sake of appearing more credible, waited until Phaedrus had as good as begged him to do so.) 

After having finally started to deliver his response, Socrates swiftly drops all such self-deprecating comments and finds fault with the discussed speech instead...unless, of course, he uses this self-effacement once again in order to undermine Lysias all the more strongly. 

“It seemed to me, who am wholly ignorant, that the writer uttered boldly whatever occurred to him” (159).   

One might think that Socrates would undermine his own rhetoric by attacking his own credibility.  Yet his credibility is bolstered.  In Plato's Phaedrus, Socrates as good as says that “you should take me seriously because I’m humble enough to say that you shouldn’t…and yet you and I both know that I’m more credible than Lysias is.” 

Not a bad approach to argument.  And yet when I try to use it, people call me passive aggressive.