Short Answer: Everyone
Long Answer: Most of the rookies, like Solomon Thomas, Reuben Foster, Trent Taylor, George Kittle, and Adrian Colbert, are all getting a taste what a win streak is all about. The first-years have been nothing but fantastic for their contributions both on and off the field. Winning can help bring the team a lot closer than it already was, and it helps boost their confidence and learning experience that can translate into next season so that they’ll get better.
Linebacker Reuben Foster has played a huge role on the defensive side of the ball with his leadership ever since the Niners respected NaVorro Bowman's wishes to release him. Foster has made a serious case for Defensive Rookie of the Year despite missing half of the season due to ankle and rib injuries.
Slot receiver Trent Taylor has become a third-down machine by converting them consistently ever since Garoppolo became the starter. His shiftiness has caused defenses problems by his ability to get open to convert those third downs, and he could have an even bigger role once the 2018 season arrives.
Adrian Colbert is a player that no one expected to perform so spectacularly considering that he was a seventh-rounder, but John Lynch knows what to look for when it comes to the safety position. Nicknamed “The Punisher” because of his hard hits, Colbert’s instincts, speed, tackling form, and intelligence has been amazing to watch on the field.
Jimmy Garoppolo has now been the starter for the past four games for the 49ers and has won every single one. This is the longest streak he has been a part of when it comes to being the leader. Jimmy G is due to become an unrestricted free agent and these games have helped him understand what kind of team the Niners are, what kind of teammates he would be dealing with, all of which will help him decide if he wants to sign a long term deal and create a legacy with Kyle Shanahan, or walk away.