SANTA CLARA, Calif. -- The San Francisco 49ers will open their offseason program Monday morning. Teams with new coaches have already begun that process and the Niners will join the teams that didn't go through a coaching staff change in kicking off their conditioning activities.

With that in mind, here's a look at five players who have much to gain and/or something to prove as we head toward training camp in July:

G Joshua Garnett -- After sitting out last season to fully recover from a knee injury and re-shape his body, Garnett has plenty to prove to coach Kyle Shanahan and his staff. The 2016 first-round pick has trimmed down to around 305 pounds in an effort to become quicker and more athletic so he can be a better fit in Shanahan's outside zone running scheme.

Though the Niners signed guard Jonathan Cooper in free agency, he is recovering from a knee injury of his own, which should open the door for Garnett to push for starting reps. This is a big year for Garnett, who was not drafted by the current regime and has work to do to nail down a roster spot, let alone a starting job.

DB Jimmie Ward -- The Niners' starting free safety at the beginning of last year, Ward is expected to open the offseason at outside cornerback. That's the position Ward left when switching to free safety in coordinator Robert Saleh's scheme last season. With Richard Sherman not expected to participate in any on-field football activities until training camp, Saleh and the Niners are hoping to get a look at how Ward might fit in their scheme as a corner.

Ward, who was limited to eight games because of a broken forearm last year, is a bit smaller than the prototype of what the Niners want at outside corner, though he could also get a look in the slot, a position he has effectively played before. The chance to offer some versatility and provide some needed depth at corner would go a long way in justifying Ward's 2018 salary of more than $8 million.

S Adrian Colbert -- Another reason the Niners are eager to see what Ward can do at corner is the emergence of Colbert at free safety. The former seventh-round pick won a roster spot last year because of his special teams ability. After injuries hit Ward and fellow safety Jaquiski Tartt, Colbert got his chance to contribute on defense and looked the part of an impact player in his six starts.

Colbert's combination of speed to run the alley and fearless hitting style makes him one of San Francisco's most intriguing young defenders. This offseason program should allow the Niners a chance to see more of Colbert at free safety and devise ways to ensure he, Ward and Tartt are on the field together on a consistent basis.

DL Solomon Thomas -- Because of an arcane league rule that prevents players from working out with their new teams until their schools have completed their final semester, Thomas didn't get to participate in the Niners' offseason program a year ago. That made his job more difficult when he arrived for training camp last year, a task made even more complicated by the fact that the 49ers asked him to play multiple positions.

Now Thomas embarks on his first full NFL offseason, and both he and the Niners are expecting a big step forward this season. In particular, Thomas wants to improve his pass-rushing repertoire, especially from the edge. Improvement from Thomas, who will have a big role in the defense in 2018, would mean improvement for the unit as a whole.

WR Kendrick Bourne -- The 49ers made notable additions at almost every position of need in free agency with the exception of wide receiver. Some of that was rooted in their refusal to get into a bidding war for the likes of Allen Robinson or Sammy Watkins, but Shanahan is also a believer in some of his team's lesser-known wideout options.

Bourne, who made the team as an undrafted rookie last year, flashed some promise in the final weeks as he posted 16 catches for 257 yards. At 6-foot-1, 203 pounds, Bourne isn't exactly physically imposing but he is one of the bigger receivers on the roster and, like Thomas, he's getting a full offseason program for the first time. A strong offseason could position him for a larger role in 2018.