Giants rookie cornerback DeAndre Baker said he didn’t know what went wrong -- or whom to blame -- for Dallas Cowboys wide receiver Amari Cooper breaking wide open on a 45-yard touchdown with 7:56 remaining in Monday night’s 37-18 loss at MetLife Stadium.

He could start with himself, if he even knew what the defensive call was on the play.

Baker admits that nine games into his rookie season, he still doesn’t understand the Giants’ scheme.

“Just the plays and everything like that,” Baker said was what he needed to improve the most. “The playbook. Just knowing the plays. Knowing what I need to do. Knowing my assignment."

Baker has started every game this season. It is troubling that he still doesn’t know the defense.

On Cooper’s late touchdown, the ESPN broadcast pointed out that Baker was playing zone defense while the rest of the defense was in man-to-man coverage, which allowed the Cowboys wide receiver to break free.

When asked if he needs to do a better job of learning his coverages Baker responded, “That ain’t a problem for me."

However, Monday night’s performance suggests otherwise.

According to Next Gen stats, Cowboys quarterback Dak Prescott finished 5-of-6 passing for 51 yards and a touchdown when targeting Baker on short and intermediate routes.

The Giants traded up to select Baker No. 30 overall in April’s NFL Draft, and he has been a disappointment. According to Pro Football Focus, Baker has a 37.8 coverage grade and is ranked 115th out of 116 NFL cornerbacks with enough snaps to qualify to be graded. He also was flagged for a 26-yard pass interference penalty when he appeared to twice grab Cooper’s arm just before the ball arrived.

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“It was a tough call, but I have to watch the film to make sure they don’t have a chance to make that call,” Baker said.

It is growing increasingly difficult to justify playing Baker simply because he was chosen in the first round.

The Giants have until 4 p.m. Wednesday to activate cornerback Sam Beal, whom defensive coordinator James Bettcher says will play on the outside if and when he’s activated. If Beal is healthy and the Giants believe he’s ready to play, it might make sense to give him playing time to evaluate the pair of young cornerbacks.

Matt Lombardo may be reached at MLombardo@njadvancemedia.com. Follow him on Twitter @MattLombardoNFL