Apostles and Early Fathers: Who Were the Real Morons?

Since Mark Shea's book By What Authority? founds its way into the conversation, I thought I'd clear up what I believe his point to have been, as well as put forth a question to him (or to anyone who feels like trying to answer it).

Shea draws his readers' attention to the way that evangelicals respond to the work of the Jesus Seminar, saying that evangelicalism is certainly correct in highlighting the absurdity of the idea that Jesus, whose knowledge and insight could penetrate into the very souls of men, was nonetheless so shortsighted that he couldn't seem to choose any disciples who would be able to correctly remember a single thing he said. In other words, how likely is it that, nine minutes after our Lord's death, his disciples would both immediately forget everything he really said and did, and invent a bunch of stuff he never said or did?

(This reminds me of the wisdom of Holden Caulfield from The Catcher in the Rye, who insisted that "Jesus needed his disciples like he needed a hole in the head." When challenged with the claim that if you reject the disciples you reject Jesus, Caulfield explained that Jesus picked his dicsiples at random since he didn't have the time to screen them properly, being busy and all.)

Now Shea's argument becomes challenging when he turns to Protestantism's response to Rome. The Protestant, Shea insists, commits the very same fallacy that the proponent of the Jesus Seminar does, only we push it back a generation. So we (rightly) deny the likelihood that the original twelve apostles completely messed up Jesus' teachings, but we also (wrongly) insist that the first generation of post-apostolic fathers misunderstood the apostles' teachings. We roll our eyes at the claim that John invented the idea that the Logos was God, while we nonetheless maintain that Ignatius delibererately inflated the authority of the bishop, or that Irenaeus concocted the theory of apostolic succession as a means to ensure orthodoxy. Thus we dismiss early church teachings on prayers for the dead, the sacrificial nature of the Mass, or veneration of Mary by insisting that the church fathers simply went astray pretty soon after the original twelve died.

The question to my Catholic readers is this: Does not Paul himself marvel at how quickly the churches of Galatia perverted the gospel they received from apostolic messengers? Is it indeed a given that the teachings of the early fathers were apostolic simply because they were in close chronological proximity to the apostles?