You should also, you know, READ the original TIGTA report, too. It is very enlightening, even with its admitted flaws. For example, the targeting was still a very small part of the total applications, and the "Tea Party" targeting was also less than a third of all targeted applications.
Read it already, and you're misstating what it says. You seem to be referring to Figure 4 on page 8--that's showing that of the applications that went for special review, about 1/3 looked like they were from "Tea Party" groups. That doesn't really say too much about whether Tea Party groups were targeted or not; of course there will be other applications that look borderline and need more review. What does show that they were targeted is that in a random sample of all applications, all Tea Party-looking groups were selected for special review. In other words, if you're not a Tea Party group, you only get special review if there's something worth reviewing. But if you are a Tea Party group, you're definitely getting reviewed. If you had read the report, you would have seen that it specifically mentions that the IRS made the same argument you made, and the report refutes that argument:
Figure 4 shows that approximately one-third of the applications identified for processing by the team of specialists included Tea Party, Patriots, or 9/12 in their names, while the remainder did not. According to the Director, Rulings and Agreements, the fact that the team of specialists worked applications that did not involve the Tea Party, Patriots, or 9/12 groups demonstrated that the IRS was not politically biased in its identification of applications for processing by the team of specialists. While the team of specialists reviewed applications from a variety of organizations, we determined during our reviews of statistical samples of I.R.C. 501(c)(4) tax-exempt applications that all cases with Tea Party, Patriots, or 9/12 in their names were forwarded to the team of specialists.