Basketball Reference has a Simple Rating System based on point differential and strength of schedule, not wins and losses. In the East, the biggest discrepancies are the Atlanta Hawks (ranked 9th according to wins and losses but 5th according to SRS), and the Miami Heat (ranked 5th according to wins and losses but 9th according to SRS).
In the West, the biggest discrepancies are the Golden State Warriors (ranked 10th according to wins and losses but 5th according to SRS) and the Dallas Mavericks (ranked 5th according to wins and losses but 10th according to SRS). SRS is usually considered more accurate by bettors, so perhaps the Hawks and Warriors are better than they appear and the Heat and Mavs are worse than they appear.