Your question has a key factual issue: Kyler Murray isn't on the Cardinals in 2026 — he's on the Minnesota Vikings, competing with J.J. McCarthy for the starting job there (from the Kyler Murray page).
The Cardinals' actual QB room under Mike LaFleur is Jacoby Brissett, Carson Beck (3rd-round rookie), Gardner Minshew, and Shedeur Sanders. Brissett is the presumed Week 1 starter, but he's in a contract holdout and has missed OTAs — which opens the door. One NFL exec predicted Beck will get a chance to play in 2026, and LaFleur has expressed confidence in Beck's familiarity with NFL-style offenses (from the Arizona Cardinals page). So if you're asking about a Beck-vs.-Brissett battle: Brissett is the favorite to start Week 1, but Beck has a real path to snaps this season, especially if Brissett's holdout drags on.