Below are some backs who had good a good second half of the 2017 season. These players should be considered by their teams to be the starter moving forward, but as usual, circumstances may dictate their spots aren't as secure as they would hope, but at the very least they proved they had the stuff to start.
Dion Lewis, RB, Patriots
The Patriots will always be a thorn in fantasy players' sides because they have a great offense, but don't have usage monsters at each fantasy position, like the Steelers for example. That makes picking New England fantasy players difficult, but injuries and a player getting hot can narrow things down, which is what Lewis did last season. From Week 6 on, Lewis saw 10 or more rushing attempts with one Week 13 exception, but in his last six games, he averaged 19.3 touches per game and 106.3 yards per game while notching five total touchdowns, three on the ground and two through the air. Those numbers ranked him as the fourth-best fantasy back during that stretch, behind Todd Gurley, Le'Veon Bell and Alvin Kamara.
Injuries have been trouble for Lewis, but it was good to see him take on a bigger role at the end of the season and in the playoffs and hold up physically. The Patriots would like to keep him from going to another team in free agency this offseason, but they also have a strict policy of not paying running backs, so we could see Lewis head off to a new team. But no matter what happens, Lewis has improved his fantasy stock and given teams a reason to give him a chance to lead their backfield instead of being a complementary piece.
Kenyan Drake, RB, Dolphins
Drake only touched the ball 42 times during his rookie season and then had just six touches through the first six games before Jay Ajayi was traded to the Eagles. Drake then was put into a committee with Damien Williams and averaged 10 touches for the next five games. Drake had some nice runs with those limited touches, but he really broke out after Williams went down with a shoulder injury. In the last five games of the season, Drake averaged 21.6 touches for 118.8 yards per game and two touchdowns. During that stretch, he was the eighth-best fantasy back in the NFL. His prospects for 2018 remain good if he can keep the lead back job. That will depend on what the Dolphins do in the 2018 NFL Draft and in free agency. There have been some rumblings of C.J. Anderson heading to play under his old coach in Miami, which would no-doubt hurt Drake's numbers, but his strong finish to the season should give him an edge to be lead back against most newcomers.
Alex Collins, RB, Ravens
Despite splitting work and having some down games against tough run defenses and losing some goal-line looks, Collins finished the 2017 season strongly, averaging 19.2 touches for 88.3 yards per game and totaling six rushing touchdowns during that stretch. That put him as the 12th-best fantasy back for the last nine weeks of the season, ahead of players like Kareem Hunt, Carlos Hyde, Christian McCaffery and so forth. Kenneth Dixon will be back from injury, and Buck Allen will continue to be shoved into service. The Ravens also could look to upgrade the position in free agency or the 2018 NFL Draft, so there's no way that Collins has the job outright going into next year, but he has proven himself in this offense and has the ability to win the job and have a good fantasy season in 2018.
Jamaal Williams, RB, Packers
Williams got a little luck last season in that he got an opportunity to prove himself after some poor games, due to injuries to Ty Montgomery and Aaron Jones. In the last eight games of the season, Williams averaged 20.4 touches for 93.3 yards per game and put up five total touchdowns. He averaged just 3.7 yards per carry, but did some nice work in the passing game to help pad his stats. The concern for Williams isn't Ty Montgomery as much as it is Aaron Jones, who put up better per-touch numbers than Williams. The good news for Williams is that his durability won out over Jones it seems and that Williams kept the lead-back job even when Jones was healthy. This situation is a perilous one for fantasy players. Jones appears to have more upside as a fantasy producer, but Williams was trusted more. I believe they'll continue to fight it out for lead-back duties, while Montgomery is either switched back to wide receiver or becomes a third-down specialist.
Marshawn Lynch, RB, Raiders
Lynch saw his touches limited in an attempt to keep him fresh, which appears to have worked, as he was very effective when the Raiders ramped up his touches in the second half of the season. Through his last eight games, he averaged 18.9 touches for 92.3 yards and racked up five total touchdowns. In his first seven games, he averaged just 11 touches for 43.4 yards and scored just two total touchdowns. I expect Jon Gruden will use Lynch more early in the season than Del Rio did, but of course at Lynch's age, who knows if he can hold up under his aggressive style of running, but there is no doubt he was still an effective runner, especially in those last eight games when he averaged 4.6 yards per carry.