Hak-Ju Lee is on a 20 game hit streak! That's excellent, right. But, I think he is the only player in the world who manages to have an OPS lower than .700 and an OBP lower .320 over a hit-streak (over his last 10 games in this case). He is even batting below .260 over this stretch. Check out his game-logs over the last 10 games (by the way: Fangraphs does provide Game-Logs for minor leaguers! They emerge as the primer source for minor league stats):
The stats over this last 10 games: .256 AVG, .313 OBP, .685 OPS and a .311 wOBA. That's below his seasonal stat-line (.264 - .327 - .674 - .323) despite the hit streak. Nevertheless, while still not hitting like we would have liked and maybe even expected, he is improving over the course of the season. His rolling 10-day wOBA shows a long tale (including a very bad month of May) with a minor peak at the end of April, followed by a June and July with a wOBA which is almost exclusively higher than .350.
Bottom line: Only determining that a player is crushing the ball because he is on a hit streak is not telling the whole story AND Hak-Ju Lee is improving.
PS: His wOBA over the whole 20-game hit streak is .4042.