Does anybody remember why Korolev was declared winner of RR1 in that tourney? Adding up the games he ends up with 17:18 while Blake has 15:14, which I would consider better. Or was Blake punished because Delpo gave up against him?
The ATP decided that Head-to-head would be the main tiebreaker, and since Korolev beat Blake, he should go through.
Percentage of games won would have been the tiebreaker had it been a true 3-way tie including Del Potro, but they determined that since Del Potro effectively retired from the event, he would no longer be eligible, therefore making it only a head-to-head with Blake & Korolev.
If Del Potro had finished the match, Blake would've advanced based on having the highest percentage of games won, but they decided that since it was a retirement the match didn't count.
Here are more details:
The relevant rule states that an incomplete match shall not count as a match played for the retiring player. This eliminated del Potro based on the tiebreak procedure for greatest number of completed matches and left only Blake and Korolev tied with 1-1 records. Therefore, under ATP rules Korolev should have advanced having beaten Blake in their round robin encounter.