Kyler Murray and Josh Rosen at the center of Cardinals’ draft mystery

Kyler Murray wanted to clear up any confusion.

Instead, he heightened the intrigue.

Two months ago, the two-sport star from the University of Oklahoma officially chose football over baseball. Even though he was drafted ninth overall by the Oakland Athletics last June, the Heisman Trophy-winning quarterback announced on Twitter that he was singularly focused on the NFL.

The mystery now is whether the Arizona Cardinals will use the No. 1 pick on Murray — angling for some of that Baker Mayfield magic — and open a defense-heavy draft with a bit of offensive flash.

If Thursday night’s first round has a pivot point, it’s right at the top. If the Cardinals take Murray, they’ll make history — no team has ever selected quarterbacks in the opening round of consecutive drafts. And if they don’t take him, it likely will prompt a quarterback-needy team to trade into the top five to get him.

Break out the magnifying glass, because everyone is trying to Sherlock Holmes what the Cardinals are going to do. General manager Steve Keim only fueled the speculation at the scouting combine in February when asked whether Josh Rosen, the No. 10 pick last year, was Arizona’s quarterback.

“Is Josh Rosen our quarterback?” Keim said, sounding as solid as quicksand. “Yeah, he is. Right now. For sure.”

Again, a team has never spent first-round picks on quarterbacks in back-to-back drafts, although the Dallas Cowboys did take Troy Aikman first overall in 1989, then used a first-round pick on quarterback Steve Walsh in the supplemental draft three months later.

Rosen was shaky at best last season, but he played behind a patchwork offensive line, had an underwhelming cast of receivers aside from the legendary Larry Fitzgerald — who’s in the sunset of his career — and had to deal with a midseason change at offensive coordinator.

There are clues that point to Murray going to Arizona. Some are compelling, while others are cockamamie. The parallels to Mayfield are intriguing. Both are undersized playmakers from the same system, with Murray following the Heisman-winning Mayfield at Oklahoma. The Cardinals made an outside-the-box coaching hire in Kliff Kingsbury, who some see as a pigskin Picasso when it comes to drawing up offenses.

When Kingsbury was struggling at Texas Tech and getting his team ready to play Oklahoma last October, the coach said of Murray: “Kyler is a freak. … I would take him with the first pick of the draft if I could.”

Now, Kingsbury and Murray have the same agent. So they could keep the loop pretty tight when it comes to sketching a potential deal before the draft opens Thursday in Nashville. And there’s the fact the Cardinals have not really tipped their hand either way, not indicating they’re going to take a quarterback, yet certainly not ruling it out.

As for the conspiracy theories, there are plenty. Word spread after the Keim comment that Rosen had removed all his Cardinals photos from Instagram. Proof the former UCLA star had one foot out the door? Not really. Turns out, all his photos were deleted and subsequently restored. Rosen also had written on Twitter before the Keim remark that his Instagram account had been hacked.

Then there was word that one Nike store in Arizona had slashed prices on Rosen jerseys to $60 from $100 — a sure sign he was as good as gone. The story lost steam, though, when the Cardinals pointed out the prices on all jerseys were reduced to make room for new inventory, and jerseys bearing the name and number of the team’s most popular player, Fitzgerald, had been marked down to $49.99 from $150.

Rosen addressed the speculation recently in a Sports Illustrated video feature on him.

“I think the best advice I’ve ever gotten, from so many different people is ‘control what you can control,’ ” Rosen said. “And whatever decisions are made, it’s my duty to prove them right if they keep me, and prove them wrong if they ship me off.”

ProFootballTalk’s Mike Florio made a case last week that Murray’s decision to attend the draft hints at him being the top pick.

Wrote Florio: “If he didn’t believe he’d be the first overall pick at a time when so many expect it to be him, would he walk into the embarrassment that necessarily would flow from sitting there in the green room while someone else becomes the first person to make the walk across the stage for a bear hug with Roger Goodell?”

Keim, along with Kingsbury, met with reporters who cover the Cardinals last week for his annual pre-draft news conference. He called having the No. 1 pick “fun” and exciting and took issue with the notion the Cardinals are trying to throw a head fake on everyone.

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“When it comes to this press conference and you guys think that this is misinformation, we’re not the only ones spitting it out,” he said. “There’s a lot of it going around. So, the fact that I don’t know what we’re doing, but everybody else does, that’s concerning.”

If the Cardinals were to draft Murray, they conceivably could hang on to Rosen, too, for a while and wait for the best deal that comes along. There are also lots of teams currently looking for quarterbacks, either as starters or backups, among them the New York Giants, Miami Dolphins, New England Patriots, Denver Broncos, and Chargers. Might one of those teams be willing to part with a first-round pick? In theory, the Cardinals would expect a lot in exchange for a young quarterback who still has a lot of promise.

We know what sport Murray wants to play. For now, everything else is a guessing game. The Cardinals consistently have said they have yet to make up their mind about what they’re going to do with the top pick.

And why is that?

“Because we’ve got time,” Keim said.

The days are turning to hours, the hours to minutes. The Cardinals are on the clock.

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Follow Sam Farmer on Twitter @LATimesfarmer