I think that's where it falters.
One, you are expecting things to go wrong and when they do, you don't feel much. Moreover, the story has no contrast. Not do the characters. Everything is dull and tensed from the very start.
There are no happy times, barring a 5 mins basketball duel, which in itself is not too fun. There are no character arcs, or no happy to sad transitions. I feel this is why the movie feels flat throughout.