Sam Darnold took to the practice field on Wednesday wearing his white Jets jersey with the green 14, giving a boost to his 0-4 team.

Sam was back.

There was no cape visible, but maybe he had it tucked into his shoulder pads.

Darnold will start Sunday against the Cowboys after missing three games while recovering from mononucleosis. It is only a rumor that fireworks were set off at the Jets training center in Florham Park after the doctors cleared Darnold to play on Tuesday.

Darnold’s return was a morale boost for a team that desperately needed one after a brutal first month of the season. But the Jets have to be careful not to treat Darnold’s return as the elixir that will solve all of their ills.

“Everybody still has to play football,” running back Le’Veon Bell said. “We can’t expect Sam to just go out there and be Superman. We know he’s a great player and he’s going to make a lot of plays, but guys still have got to do their job. We still have to protect him. We still have to make plays for him.”

There is no doubt that Darnold will improve the offense. How could it get any worse?

The unit has been abysmal over the last three games with Trevor Siemian and Luke Falk at quarterback. The Jets have converted just 5 of 40 third-down tries in that span. They have scored one offensive touchdown without Darnold. They have 233 total yards over the last two weeks with Falk running the show and 130 passing yards. The Jets have 454 passing yards this season. Cowboys quarterback Dak Prescott, this week’s opponent, threw for 463 yards last week against the Packers.

So, the only direction for the Jets offense to go is up. Darnold will elevate the play of everyone around him. He will recognize defenses better than Falk. He will be able to elude the rush better than Falk. He will make Adam Gase look better as a play-caller. Name it, the Jets should improve.

But the Jets need to be careful to not expect a miracle from Darnold.

Remember this is not a 10-year veteran returning to the starting lineup. He is a 22-year-old who will be making his 15th career start Sunday. Think about that: Darnold has not even started a full season of NFL games yet.

This season was supposed to be about seeing if Darnold can make the leap that some second-year quarterbacks make. Could he put his rookie mistakes behind him and elevate his game? We still don’t know the answer to that question. He did not play great in Week 1 against the Bills. Now, it turns out he was already feeling the effects of the undiagnosed mono and had not slept the night before, so that explains some of the mistakes.

Entering this game and his return, though, it feels like we have lost the perspective of Sam as an NFL sophomore and he is just being viewed as Sam the Savior.

“Anytime your starting quarterback comes back, guys are going to be excited,” Gase said. “The good thing is, the way he looks at it is, he wants to come in and do his job. I don’t think guys are looking at is, now that he’s back all will be all right, they know we have a lot to clean up.”

The offensive line is coming off a dismal performance in Philadelphia where it allowed 10 sacks. Darnold can help with calling protections and also being more mobile than Falk, but the line issues won’t vanish because of his presence. The defense has played pretty well, but where is the pass rush? The Jets only have six sacks in four games. Darnold won’t be chasing Prescott on Sunday.

As Darnold threw the ball all over the field at practice on Wednesday, the smiles were back on the Jets’ faces.

Sam was back.

There is no question that the Jets are a better team with him in the lineup. Just don’t expect him to make them a good one overnight.