Who excels under pressure?
Solution 1:
A player who doesn't buckle under pressure, could be said to deliver the goods. And I would also describe such a player as being ruthless and consistent.
However, a slang term which fits the Op's request is clutch:
to perform under pressure
In the last few seconds of a close game, only a player with clutch can lead the team to victory. (Derived from the clutch mechanism in a manual car, where perfect timing can mean the difference between a launch and a stall)
A reputable baseball coach has this to say: 1
If a hitter is averaging .333 and gets a hit one time in three clutch situations, he is performing well in the clutch... normal performance under pressure is the goal, not super performance.
All too often an athlete gets the reputation as a "great clutch player" because of one or two performances that got a lot of media attention, but the truth of the matter is most of the time a "great clutch performer" is one who performs normally under pressure.
Solution 2:
Consider
- rise to the occasion
- rise to the challenge
- step up
- thrive in a crisis
- thrive on adversity
If the player or team were doing poorly and then rallied, you could say
come back from the dead