Rough start to second half hasn’t soured Knicks on rookies’ potential

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Mitchell RobinsonOn a roster filled with former lottery picks, no Knicks player has demonstrated more potential this season than the team’s most recent second-round selection, Mitchell Robinson.

But in this miserable season, no progress comes without pain.

Leaving for the All-Star break on the best stretch of his rookie season — averaging 11.5 points, on 72.5 percent shooting from the field, with 8.5 rebounds and three blocks in just 22 minutes over a six-game span — the 20-year-old center returned with one of his worst performances of the season. In Friday’s loss to the Timberwolves, Robinson played 13 minutes, his fewest since Jan. 28. He missed his only two shots, going…