MOBILE, Ala. — A day that began with height measurements and weigh-ins and included a media day was capped with the first of three scheduled days of practices at Ladd-Peebles Stadium.

The South team, coached by the San Francisco 49ers coaching staff, hit the field first for an hour-and-a-half on a breezy day flavored with high humidity and a drizzle that intensified from time to time.

The North team, led by the Oakland Raiders coaching staff, took the field at 3:30 p.m.

By dinner time, Western Illinois defensive tackle Khalen Saunders had become a father.

Saunders' fiancée was initially due on Jan. 31, but she went into labor early in Chicago. She and Saunders, along with his family, decided it was best for him to remain at the Senior Bowl because of the event's importance in helping him make an impression on an NFL team.

Here are four takeaways from Tuesday's session:

1. The eyeball test is important

The Senior Bowl is a convention of sorts where coaches and scouts reconnect with former comrades turned competitors, but the reason for the reunion is the value placed on seeing prospects compete against quality competition during the practices and games.

Reps between offensive and defensive linemen drew heavy attention from personnel department members interested in players who can protect or affect a quarterback.

2. Information age continues to explode

There has never been more information available for NFL clubs when deciding how to invest draft picks, the rarest capital in the league.

Thanks to information from Zebra Technologies, evaluators can enhance their eyeball test with scientific measurements.

For instance, everyone could see Ohio State receiver Terry McLaurin zip across the turf in a 1-on-1 rep, but they also can know that he had the top speed of the day for the North:

Houston cornerback Isaiah Johnson had the fastest top speed of the day for the South:

Maybe Johnson will be matched up against McLaurin for a play or two Saturday?

3. Pump up the volume

The rules of the game limit the types of formations that offenses can do, as well as pre-snap motions and shifts in order to steer the game toward offering direct matchups for evaluations.

That doesn't mean that offensive-background head coaches Kyle Shanahan and Jon Gruden are taking it easy on quarterbacks.

Gruden mentioned during a media session Tuesday that he was grateful that Shanahan would be limited in what he could do before the snap. He added, however, that the coaches increased the volume for what they want to see from quarterbacks executing three-step and five-step drops as well as making throws when moving out of the pocket.

4. Keep kicking or repping

South kicker Cole Tracy had an auspicious start to field goal reps, missing his first wide right and his second wide left on the first day of working with long snapper Nick Moore and holder Jake Bailey.

Tracy's quick bounce back was just one example of the importance of moving past a bad rep.

That ability is important at every position on the gridiron.