Football may be the ultimate team sport, but there are always a few players who serve as essential pillars on any roster.

They don’t have to be the most talented. Whether it’s due to experience or a specific schematic fit or a lack of options behind them on the depth chart, these are the players that would be the hardest to replace. Now that spring football has provided a better picture of what 2017 might look like for the Big Ten and its 14 teams, it’s easier to see which players could create the biggest problems if they’re not able to play for some reason next fall.

Here’s a look at the league’s five most indispensable players. They may not necessarily be swimming in personal awards at the end of the season, but their teams' success will depend on them being in the lineup.

Penn State S Marcus Allen: The Nittany Lions’ leading tackler from a year ago helped clean up a lot of stray ball carriers while the group in front of him worked through some depth issues at linebacker in 2016. After making 110 stops as a junior, he’s back for a final season as the leader of a secondary that could be a difference-maker in Penn State’s attempt to defend its Big Ten title. Allen, heading into his fourth season as a starter, is an important on-field director, especially since his group has to replace safety Malik Golden and might be without returning starter John Reid (knee injury) at cornerback for the year.

Wisconsin QB Alex Hornibrook: Hornibrook didn’t play in Wisconsin’s spring scrimmage, which made it perfectly clear how important he’ll be to the offense’s success in the fall. Neither of his backups -- early enrollee Jack Coan and redshirt freshman Kare' Lyles -- looked ready to take the reins as of the end of April. Not that it’s a huge problem to throw a rookie in at quarterback (just ask Hornibrook, who started nine games and threw for 1,262 yards after winning the job a few games into his first year on the field in 2016), but it’s clear that the incumbent lefty remains a step ahead. With a healthy Hornibrook and the usual Badgers defense, Wisconsin is a favorite to win the West. Without him, its outlook gets a little dicey.

Michigan LB Mike McCray: The lone returning starter from a loaded defense, McCray is responsible for helping a young and talented pack of players around him get used to college football on the fly. The redshirt senior battled injuries through most of his career before finding his groove with 76 tackles and 4.5 sacks last season. He said after Michigan's spring game that his confidence was at “an all-time high” and that he thinks the whole unit can be faster than it was a year ago. When the Wolverines get up to full speed, it will largely be McCray’s job to keep them all running in the right direction.

Ohio State OL Billy Price: The best news to come out of the Buckeyes’ blowout playoff loss on New Year’s Eve was Price’s postgame announcement that he would return for his senior season. It’s not very often that a team can replace a Rimington Trophy winner at center with another player who is already an All-American. Price is shifting from guard to center to take Pat Elflein's place in the middle of an Ohio State line that should be able to win most battles in the trenches. Price’s leadership and versatility on the line could be the difference between a very good unit and a championship-caliber group.

Indiana LB Tegray Scales: Scales led the nation in tackles for loss (23.5) and the Big Ten in tackles (126) during his junior season with new defensive coordinator Tom Allen. Allen is now the head coach, and the Hoosiers are shaping up to be a team that will need more help from its defense than it did in the Kevin Wilson era. Scales provides a consistent tackler and an explosive playmaker in the middle of a 4-2-5 scheme at Indiana, which needs to replace his counterpart starter at linebacker. If the Hoosiers expect to make it to a bowl game for a third straight year, Scales will have to be one of country’s most productive players again in 2017.