Randball: Michael Rand 

After deciding to trade for Sam Bradford late in the 2016 preseason when Teddy Bridgewater was injured and backup Shaun Hill was deemed not desirable enough as a full-time starter, the Vikings probably didn’t need much more convincing when it comes to the value of having a good backup plan at QB.

But then 2017 rolled around and said, “Case closed.”

This is only a partial pun because it’s only partly related to Case Keenum, the low-cost backup who not only saved the season but took the Vikings on a run to the NFC title game.

Further evidence arrived across the border, when the Packers stubbornly stuck with overmatched Brett Hundley while Aaron Rodgers mended. With a better backup, Green Bay probably would have made the playoffs and had a healthy Rodgers in the postseason. And in the playoffs, Philadelphia backup Nick Foles caught fire and led the Eagles to a Super Bowl title.

Good teams don’t need competent backup quarterbacks most years, but they find out quickly what can happen to a season when they need one.

That brings us to the 2018 Vikings. They signed Kirk Cousins to a fully guaranteed three-year contract, making him the highest-paid (for now) QB in the game. Part of Cousins’ appeal is that he started 16 games each of the past three seasons.

In the same week, they added Trevor Siemian as a low-cost backup who started 24 games over the past two seasons. Vikings fans will be thrilled if Siemian never throws a meaningful pass in purple. But they should also feel good knowing there’s a viable Plan B, just in case.

Michael Rand is the senior digital writer for Star Tribune sports and keeper of the RandBall blog at startribune.com/RandBall.

In terms of backup quarterbacks, few signings were as prudent or paid off as well as the Vikings’ signing of Case Keenum, who is now in Denver. To field a backup behind Kirk Cousins, the Vikings traded for Trevor Siemian, formerly of those same Broncos.

The Vikings are hopeful Cousins starts (and finishes) every game, but if he doesn’t, what are they getting in Siemian? Well, they’re getting someone whose profile was similar to Keenum’s before Keenum had his breakout year.

In the 2016 season, Keenum was rated 31st among quarterbacks who took at least 25 percent of their team’s snaps, according to Pro Football Focus. Five slots above him was Siemian at No. 26. Keenum had a slightly better completion percentage (60.0 to 59.5), and their yards per attempt weren’t far off (7.0 for Siemian, 6.84 for Keenum).

In 2017, Siemian didn’t improve. He still had a completion percentage below 60 (59 percent) and his yards per attempt were 6.55. He was the 32nd-rated QB, according to Pro Football Focus. Keenum improved to 14th.

Of course, Siemian is coming from a different situation. He had better receivers in Denver (Demaryius Thomas, Emmanuel Sanders) than Keenum had under Jeff Fisher’s regime with the Rams.

The backup QB market is often ugly. You have to find value where not many others see it. The Vikings were spoiled last season, but the front office saw something in Keenum others didn’t and it paid off. Perhaps they also see something in Siemian that would make him a viable starter in case of Cousins’ unavailability. The numbers don’t foretell great things for Siemian, but neither did they for Keenum.

Chris Hine is the lead writer for North Score, the Star Tribune’s new sports analytics beat. Find his stories at startribune.com/northscore.