It happens when a new regime arrives, and it happened when Eric Mangini took over as head coach of the Browns almost seven months ago.
In an effort to rebuild the team the way he wanted it to be, Mangini grabbed a big, wide broom and cleaned a lot of players out of the locker room by releasing them, trading them or choosing not to re-sign them.
For that matter, remember Sean Jones?
Pool remains, though.
"Somebody asked me the other day, ‘Do you think the coaches like you?' " Pool said following Friday morning's training camp practice. "I said, ‘Well, yeah. I'm still here, aren't I?' "
That may sound like a simplistic statement, but it says a lot. It says that even though it was former general manager Phil Savage who chose him at the top of the second round of the 2005 NFL Draft, he still has value to Mangini when a lot of other ex-Browns didn't.
"Like I said to that reporter the other day, I know the Browns must like me," Pool said.
After a rough start together in the first part of 2007, Pool and Jones became a good combination in the back of the Browns defense. Jones was second on the team with four interceptions, while Pool was among three players who had three, a career high for him. He had two in 2007 and one in both of his first two years for a total of seven.
"I don't want to say the transition has been easy, but really, it has been easy," Pool said. "Back when Sean and I were first together, we were two pretty young guys who hadn't played a whole lot. Now, with Elam and me, you've got two older guys who have been around a while. That really helps.
"And anyway, football is football. As an older player – I'm in my fifth year now – you're expected to know certain things about the game. You're expected to have no trouble making transitions like this."
Though it is very, very early -- camp isn't even a week old -- Pool and Elam look like they're gelling to this point. No big problems yet. They're getting a little better every day.
"It's not about just me and Elam, though," Pool said. "It's also about (fellow safeties) Hamza (Abdullah) and Mike (Adams) and all of us learning to play with the cornerbacks."
Despite the fact his 40 solo tackles last year tied a career best, Pool came in a few pounds heavier this year in order to pack a little more of a wallop. He's at 210, up from 205 in 2008.
But has it slowed him down?
"No, not at all. I was 220 one year in college and I played fast," the former Oklahoma Sooner said.
Pool's NFL career got off to a slow and painful start, as he suffered a concussion against the Cincinnati Bengals on the opening kickoff of the first game of his rookie season of 2005. He admits that it set him back, and it wasn't until the 2007 season, after he had been installed as a starter and he and Jones began to work in concert, that he seemed to totally catch up.
Pool chuckled and said, "It's like night and day for me from then to now."
Which is probably why he has survived the first regime change of his career and is still with the Browns.