It has been happening, Stillers usually shy away from it though, so not as noticeable. They have a promote within mentality, but have grabbed some guys from others’ practice squads. It is all part of modern salary cap/free agency NFL. They tweak the rules every few years, so it might be a bit more now. Guys that aren’t already signed somewhere aren’t signed for a reason. Injury prone, too old, head case or just not as good as what they think they are money wise. You can find a gem in the rough, but guys that are likely multi year starters are on someone’s roster. It makes the dynamics of the NFL very complex. Always hear people saying “we need this or we should get this guy”, but most times with others contracts, cap hits, etc it is just not feasible.
As noted before, Browns are pretty much all in this season cap wise. Super Bowl or bust, since it will be impossible to keep their current roster with Watson’s contract. They have to do some sort of short term gamble.
Stillers don’t ever do that. Which is why they are always competitive, but never great. That said, it has been about 10 years since they have been “one player away” from being a real competitor. They are well more than one player now. Maybe with Khan, if they get to be within a player or two of being a real contender, they will make that move. It almost certainly won’t be a QB. Just due to the crazy contracts that top tier QBs require. I can’t see the Rooney’s ever allowing that.