In the span of three years, the San Francisco 49ers have gone from a team to beat in the NFC, to a squad everyone wants to have on their schedule. A big reason for that was the departure of Jim Harbaugh, who was the driving force behind the franchise's run of three straight runs deep into the playoffs from 2011 to 2013.

The second reason? Colin Kaepernick. He's suffered a fall from grace since signing a $126 million megadeal in 2014 and is no longer the shoo-in starter at quarterback. Instead, he'll battle Blaine Gabbert for the starting job, a competition that Kaepernick should seemingly win, but may not end up taking from Gabbert.

Unlike in year's past, Kaepernick isn't the most important player on the team. In fact, he's far from it. If the 49ers are going to have any success in 2016, there are several guys that that are more important to the team's future than he is.

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Here are five key players that are crucial to San Francisco's season as OTAs got underway on Tuesday.

Blaine Gabbert, QB

If it's not Kaepernick, it's (most likely) going to be Gabbert under center for the Niners this year. The former No. 10 overall pick of the Jaguars in 2011 has been deemed a bust by just about everyone, but he has a shot to resurrect his career in San Francisco. He started eight games for the 49ers in 2015, and while he didn't play particularly well, he wasn't the sole factor in the team's 5-11 record. He completed a respectable 63 percent of his passes and had 10 touchdowns to seven interceptions, while also adding 185 yards on the ground. His wide receivers didn't do him any favors, either, dropping the ninth-most passes in the NFL, according to Sporting Charts.

Carlos Hyde, RB

What does a team do when it doesn't have a star quarterback? Run the ball. Fortunately for the 49ers, they have a solid running back in Carlos Hyde, who is a Pro Bowl-caliber player when healthy. He was far from that in 2015, though, starting just seven games due to foot injury. Hyde possesses a combination of power and speed, which are ideal traits for a running back. Though he only has 803 yards in two injury-laden seasons, the 49ers expect big things from the former Buckeye -- and they'll need an outstanding season from him if the offense hopes to move the ball. The offense should be run-heavy, especially if Kaepernick is under center, and Hyde will be a big part of that.

NaVorro Bowman, LB

After missing all of 2014, NaVorro Bowman returned to his All-Pro form, making the first-team in 2015, just as he did from 2011 to 2013. He racked up 154 tackles in 16 starts to go along with 2 1/2 sacks and one forced fumble. More important, he's a vocal leader in the middle of the defense and makes the front seven measurably better when he's on the field. Bowman can help shut down opposing rushing attacks when healthy, which he has been every year outside of 2014. He'll need some help, though, as the 49ers allowed the fourth-most rushing yards per game last season.

Tramaine Brock, CB

There are few teams thinner than the 49ers at cornerback. Tramaine Brock is the No. 1 corner for San Francisco, which is saying something about the talent it has at the position. He was decent in 2015, starting 15 games and recording three interceptions, but his play will need to be elevated if the 49ers plan to limit opponents through the air. If Brock gets injured at any point in the season, something he's dealt with in his career (just three games played in 2014), the 49ers are in serious trouble. That makes him a key part of the defense, and a crucial factor in the team's success.

Joe Staley, OT

The Niners obviously have a bad situation at quarterback, but it will be made even worse if the starter can't stand upright in the pocket. The 49ers' offensive line allowed the second-most sacks in the league last season, and that layed a role in the team's poor quarterback play. Joe Staley is a key cog on the offensive line, surrendering just five sacks in 2015. While he may not be the star he once was at left tackle, he's arguably the best lineman on the roster, and he also plays the second most important position on offense. San Francisco and its quarterbacks will need Staley to put together a Pro Bowl-type season.