The NFL takes a snapshot of league rosters only once during the year, Opening Weekend, because otherwise they're fluid the rest of the year.
In 2019, Alabama had the most players of any college, 56, on active 2019 NFL Kickoff rosters. The Crimson Tide also saw the most NFL players on season-opening rosters in 2018, with 44.
Ohio State (44) ranked second in 2019, after previously ranking fifth with 36 the previous season season.
That figure didn't include any Crimson Tide players who transferred elsewhere and made the league like New Orleans running back Alvin Kamara.
As for why Saban has been so successful, BamaCentral's Christopher Walsh touched upon it in his book "Decade of Dominance."
“Alabama has always had the name brand, recognition, the historical tradition,” former NFL general manager and Senior Bowl director Phil Savage said. “It’s always resonates with people, but I also think that it was just a stop on the circuit [for scouts]. There was not a lot of distinction between going to Alabama versus Tennessee, Auburn or Georgia. It was just one of the stops.
“Once Nick Saban got there, honestly in the Southeast it has become the stop.”
Besides the Crimson Tide’s obvious high level of talent, there are three other major contributing factors.
First, Saban’s “process” is comparable to how an NFL team runs things, with schemes that are both complex and pro friendly. Former safety Mark Barron went so far as to say that learning the Crimson Tide’s defense was tougher than anything he’s had to do in the NFL, and he’s not only switched teams but positions — from safety to linebacker.
“It’s very difficult,” former Alabama linebacker Rashaan Evans said in agreement. “It just takes time.”
Saban also had an open-door policy to the NFL and was known for being accommodating to scouts, who are often seen on the sidelines during practices. In addition to checking out prize prospects for the next draft, with Alabama having quality players at every position, it gave them an immediate baseline by which to evaluate all others that they’ll see.
“When I was the scouting director of the Ravens (1996-2002), one of the first stop I made every in August was the University of Miami,” Savage said. “I knew I was going to see players at virtually every position and now I could start making comparison right away with Ed Reed at safety, Kellen Winslow at tight end, whomever. Alabama is very similar.”