The country star sure made it seem that way when we got him out in L.A. this week ... 'cause he told us he straight-up forced the Cards' GM to take the Oklahoma QB!!!

"I told Steve Keim that we wouldn't be friends anymore if he didn't take [Kyler] No. 1 in the draft," Blake says.

FYI, Blake is a diehard Cards fan -- he says he's backed the team for more than 20 years -- and says he's got a hell of a relationship with A LOT of high-ranking execs on the team.

So, he really might've swayed Steve!!!

Of course, the pick seems like a no-brainer now (Kyler's KLLIN' it this season) ... but at one point, a lot of people had their doubts about the Heisman Trophy winner.

In fact, Joe Theismann told us way back in April he thought Kyler was making a HUGE mistake by picking football over baseball!!!

But, Shelton says he was always super confident that Murray would be a star for his favorite squad ... telling us, "I love Kyler Murray. I love him."

As for what he thinks Kyler is going to accomplish for the Cards this year ... Shelton gave us a big, fat guarantee -- saying Arizona will make the playoffs!!!