I'm from South Carolina, went to undergrad at Clemson during the Shyatt era and then returned for the Purnell era. Purnell had Clemson rolling, and posting winning records in the ACC, winning 20 games a year, and recruiting well. That was the fact of the situation. Here is Clemson's record before Purnell and during Purnell:
Larry Shyatt:
20-15 (first post Rick Barnes season) (5-11 ACC)
10-20 (4-12)
12-19 (2-14)
13-17 (4-12)
15-13 (5-11)
Oliver Purnell:
10-18 (3-13)
16-16 (5-11) NIT
19-15 (7-9) NIT
25-11 (7-9) NIT Runner up
24-10 (10-6) NCAA T
23-9 (9-7) NCAA T
21-11 (9-7) NCAA T
So, does this look like a program trending up or down under Purnell? Oh, and his final class included 2 4* players and a 5* player, which, you being a big Clemson fan and all, should know people were really excited about.
Wait, what about fan attendance in Purnell's final year, I mean, since folks were so frustrated, I'm sure no one was showing up.
"The year before Brownell was hired, when Oliver Purnell went 21-11 in 2009-10, the Tigers averaged 9,465 fans per game, close to the building's 10,000-seat capacity. In Brownell's first campaign, that number dropped to 8,289 while Clemson won 22 games and returned to the NCAA tournament."
So it seems like Purnell was pretty much selling out Littlejohn. Again, since you're so in touch with Clemson you should realize that this simply doesn't happen very often.
Here is another Clemson fans take on Clemson Oliver Purnell:
"The vast majority of Clemson fans were happy with the job OP had done. While it would not have surprising for other schools to come after OP given the job he was doing at Clemson, the sudden nature of his departure was shocking and disappointing for almost all. There was some frustration and concern that his teams had become one-dimensional and could not get past the first round of the dance, but those that called for his head were a scant few."
So anyway, these are the facts. You can dispute them with your vague "I know donors" thing, but I'm not sure that will be very effective.