SANTA CLARA >> Patrick Taylor Jr. concedes there are times when he wondered if this day would ever come.

“Certain times it crosses your mind,” Taylor said. “But you have to stay consistent and disciplined to your process.”

Taylor is next man up in the running back room, with rookie Isaac Guerendo ruled out Friday before the 49ers embarked on a trip to Miami to face the Dolphins today in a battle of 6-8 teams.

Also ruled out was left tackle Trent Williams (ankle). Listed as questionable were edge rusher Nick Bosa (hip/oblique), linebacker Dre Greenlaw (Achilles) and edge rusher Robert Beal Jr. (ankle).

Taylor, 26, who is in his fourth season and first with the 49ers, has played in 44 games. Counting fullback Kyle Juszczyk, who opened a game in a single back set, Taylor is the fourth starting running back for the 49ers this season, joining Jordan Mason, Christian McCaffrey and Guerendo.

In three seasons with Green Bay, Taylor played in 34 games with no starts and has stuck in the NFL largely through his work on special teams. He has 14 carries for 50 yards and a touchdown for the 49ers. For his career, Taylor has 79 carries for 311 yards and two touchdowns.

The most Taylor has ever carried the ball in a game was 11 times for 53 yards for Green Bay against the Detroit Lions in 2022.

It isn’t new territory for Shanahan, who has had 15 different running backs start games in the regular season or playoffs since joining the 49ers in 2017.

The first was Carlos Hyde, who was followed by Matt Breida, Alfred Morris, Jeff Wilson, Tevin Coleman, Raheem Mostert, Jerick McKinnon, Elijah Mitchell, Trey Sermon, Deebo Samuel, McCaffrey, Mason, Guerendo and Juszczyk.

Potentially available to back up Taylor are Ke’Shawn Vaughn and Israel Abanikanda, with the possibility that Samuel could get snaps as a running back as well.

“He’s been here since training camp, he’s done a real good job for us, played in this league before with Green Bay and when he’s gotten opportunities with us he’s run the ball well,” Shanahan said of Taylor. “When he hasn’t run the ball, he’s helped on special teams. A big opportunity for him and I’m glad we got him.”

In college at Memphis, Taylor gained 2,884 yards on 536 career carries with 36 touchdowns. He battled through a Lisfranc foot injury that led to him being undrafted.

Taylor attributes the 49ers’ ability to plug and play running backs effectively in part to the instruction of position coach Bobby Turner.

“He does a great job making sure we’re prepared going into a game and he has a lot of confidence in us to play well,” Taylor said. “When we get out there, it’s just playing freely and not hesitating.”