Starters in, starters out. That's college football. Players' eligibility expires and they leave for the rest of their lives, which might include the NFL or not.

And they leave behind shoes of various sizes that need to be filled.

In alphabetical order, we will survey each Pac-12 team’s most notable void. Today we look at Colorado.

Biggest shoes: WR Paul Richardson

Richardson leaves Colorado as one of its most accomplished receivers. He’s third all-time in receptions (156), fifth in receiving yards (2,423) and second in touchdowns (21). He posted three games of 200 yards receiving or more, a school record, and his nine games of 100 receiving yards or more is fifth in school history. He earned Colorado’s MVP award and was an all-league first-team pick. His shoes, which were quite fleet-of-feet, are not easy filled.

Stepping in: Several options, but by-committee seems the most likely.

There was hope that Jeff Thomas would be able to fill in, but his transfer in January left an additional void in the receiver corps. At least for right now, it’s looking like a rotation of D.D. Goodson, Devin Ross, Bryce Bobo and/or Elijah Dunston. Goodson caught 22 balls last year for 306 yards and two touchdowns. He has outstanding speed and of his 22 catches, 12 were for 10 yards or more and three were for 20 yards or more -- including a 75-yard touchdown. Of the group, he might be the strongest big-play threat. Ross caught six balls for 24 yards last season. Nelson Spruce is a steady presence on the other side, but lacks the breakaway speed Richardson had. There are a couple of incoming freshmen who might work themselves into the mix as well.