As you read this, there are about 250 NFL scouts and GMs crisscrossing the country visiting college campuses and getting a final look at the 2009 draft class.

The entire month of March is strictly dedicated to this process. Each school will set a pro day and invite all NFL teams. The Combine testing drills are duplicated and there are additional position-specific drills. For example, QBs will throw to receivers, defensive backs will do DB drills and linemen will run over, around and through blocking bags.

Pro days are usually arranged and operated by the college strength and conditioning coaches. Football powers like USC, LSU, Florida, Michigan, Penn State and Oklahoma set dates that are convenient to their program. The rest of the schools work around these dates. For example, if USC is set for March 23, UCLA might set its pro day for March 24 and San Diego State for the day after. The evaluators simply migrate like crows from one corn field to another.

Here are a few pro days that were career changers:

THE TRUTH

In 1996, when I represented three offensive linemen from Texas A&M-Kingsville, including first-round pick and future Pro Bowler Jermane Mayberry (Eagles), I also had a wide receiver named Karl “The Truth” Williams. Karl and I faced two challenges as 30 teams descended on campus for pro day. First, most clubs sent their offensive line coaches. Second, the Javelinas were a running powerhouse, and Karl only had a handful of receptions that season. Plus, he hadn’t been invited to the Combine and didn’t light it up in the 40 that day.

After the scouts were done salivating over the studly group of linemen, who were recruited and groomed by current Eagles O-line coach Juan Castillo, I could only convince one scout to stay and work out Karl. He was Rustin Webster of the Buccaneers, now with the Seahawks, who was willing to stay in beautiful Kingsville for one more hour to work out the skinny receiver.

Result: Draft weekend came and Karl was not picked. However, about an hour after the draft I received a call from the Cowboys and Bucs asking to bring Karl to camp as an undrafted free agent. Needless to say, I sent Karl to the Bucs, and he went on to play nine years for Tampa Bay, becoming the team’s all-time leading punt and kickoff returner. Rustin, Karl and I thank you.

FIVE KEPT HIM ALIVE

Safety Chris Harris from Louisiana-Monroe University was probably a bit worried when only five scouts showed up at his pro day. Chris wasn’t invited to the Combine, but the scouts who saw him were rewarded with an impressive workout. Usually, players who don’t get invited to the Combine don’t get drafted. However, Chris was taken in the sixth round by the Bears and eventually was traded to Carolina. He was one of the leaders of the Bears’ Super Bowl run in 2006 and is still a starter for the Panthers. One of the five scouts who saw him that day worked for the Bears.

ONE MORE CHANCE

Bears starter and Pro Bowl cornerback Nathan Vasher of Texas was a potential high-round pick going into the 2004 Combine. However, he didn’t run at Indy and clocked a horrible 4.7 at his pro day. His stock dropped, and he was expected to be a late-round pick or an undrafted free agent. After his workout, a regional Bears scout walked up to him and said, “I know you can run better. I’ll be back in 10 days to time you again.” Ten days later, the Bears scout clocked Nathan in 4.5 for the 40, and Chicago proceeded to draft him in the fourth round. He had eight interceptions in 2005.

CARROLL, RUSSELL, CASSEL

In 2005, the USC pro day was all about first-day draft picks: WR Mike Williams, DT Mike Patterson, DL Shaun Cody and LB Lofa Tutopa. After the workout, head coach Pete Carroll asked if any scouts wanted to stay and work out some back-ups and special teams players. As a herd of evaluators hustled to their cars, eight remained for the “off, off Broadway” production. One scout, Matt Russell (currently with the Eagles) was so impressed with QB Matt Cassel that he convinced his bosses with the Patriots to make the investment in him in the seventh round. And of course, you know the rest of the story.