Jordan retired near peak performance, switching to baseball. After playing professionally, but lacking the same level of success, Jordan left baseball and eventually returned to basketball. After his return, though he was said to have developed significantly personally (and as a teammate), his gameplay was tepid, and didn't have the same spark that made him so dominant.
Now, let's look at Flash, who retired near his peak performance in BW. The winstreak he had right before he lost to Grape is a pretty good example of how strong he was before Kespa started looking at SC2. Of course, Flash was far more successful in sc2 than jordan was in baseball, but he certainly lacked the dominance that he had in BW.
Hopefully, when he returns to Afreeca, his experience will be far better than Jordan's upon his return to the NBA. Bisu and Sea have done extremely well, showing that successful players can return to the stage. But far more mediocre players are also doing great. Larva, Hero, Mong, HiyA, Last, and Killer have shown that you don't necessarily have to be one of the Kespa greats.
Heck, Jordan even owns (the worst team in the league), Charlotte. Flash will likely go this route eventually, joining the coaching/managing staff of KT (as he said in one of his retirement interviews).
Whether he succeeds or not, viewing Flash's experience in SC2 as just one period of his time in esports has eased the discomfort I initially felt upon learning of the retirement of someone who I've looked up to for his hard work and dedication for many years.