Bill Barnwell at ESPN makes the case that the Steelers made the right decision by resting their starters in Week 17 (and still beating the Browns lol)
Should teams rest their players?
I lean toward yes for a few reasons:
There's no strong evidence it impacts team performance in the postseason
For every instance of a team flailing once it gets into the postseason, such as the 2017 Rams, we can find one or even two examples of a team that rested its players without any repercussions. I can't say for sure that rest helps, but the evidence about how a break in Week 17 impacts on-field performance is mixed and unclear at best.
Teams that don't rest players lay eggs, too
Teams break bad all the time. Last year, the Giants won in Week 17 with a full complement of players and delivered a dud at Lambeau the next week.
Likewise, teams might gain inspiration from playing well in Week 17. The Giants famously credit their postseason run to sending out a full complement of talent against the Patriots during Week 17 of the 2007 season, with their 38-35 loss eventually yielding a 17-14 win in Super Bowl XLII. You can make anecdotal arguments in every possible direction.
There is strong evidence it keeps players healthier
The one thing we can say for sure is that the chances of a player getting injured during Week 17 are significantly higher on the field than they are if the player remains on the sideline. (Teams worried about a star being rolled up on might wish to position him in a luxury box, and players can get hurt in practice like Artie Burns did this week, but the risk reduces to basically nil.)
As I mentioned earlier, the 2009 Patriots played Welker in a Week 17 game against the Texans only for Welker to tear his ACL. The Pats kept Brady in until midway through the fourth quarter, but it didn't help. They hosted the Ravens the following week in the wild-card round and were down 14-0 after nine plays thanks to an 83-yard Rice touchdown run and a Suggs strip-sack. Brady finished with just 154 yards passing and three interceptions on 42 attempts in a 33-14 home blowout.
Besides, even if we poke deeper into the Rams argument, there's not much there. Donald had a monster game. Gurley ran the ball well but struggled as a receiver. Was he rusty only in the passing game? Goff struggled, but the biggest problem for the Rams on Saturday night was Pharoh Cooper, who shockingly made two key special-teams errors. Cooper was hardly rusty; not only did he play in Week 17, but the South Carolina product started that game as a wideout and was targeted four times.
I suspect the Steelers aren't concerned about what taking Week 17 off might do to them, either, given that they went down the same path last year. Again facing the Browns, the Steelers sat Roethlisberger, Bell, Brown, Maurkice Pouncey and Stephon Tuitt in advance of their wild-card game against the Dolphins. Roethlisberger subsequently hit Brown for touchdown passes of 50 and 62 yards on Pittsburgh's first two drives of the postseason, and Bell plunged in for a 1-yard score on their third.
Mike Tomlin's team won 30-12 and then beat the Chiefs before being routed by the Patriots in the AFC Championship Game. If the Steelers don't make it to a rematch with the Patriots (or a home game against the Titans) next week, it will be because of what the Jaguars do on Sunday as opposed to a decision Tomlin made to give his stars a break last week.