To make the SoS useful across the board you can remove the teams' own record.
For example if we take NYXL's stage 1 SoS and remove their own 7-0 it's 21-21. A perfect 0.500, yet the original SoS would've told us that they had an easy stage 1. If we let those teams play one match each against the Washington Justice it's a reasonable assumption that it would've been 28-21. In other words against the same teams New York would've had an easy SoS and Washington would've had a hard SoS. That's obviously not the point of SoS. You want it to tell you if team A had a better record because they're better than team B or because they had an easier schedule, not the fact that A had a better record.
Of course this also removes the standard arguments of "A only got #1 because they had an easy schedule" and "My team doesn't actually suck, they just got fucked by the schedule" but we're not here to coddle anyone, we're here for accurate statistics.
In theory we'd also have to remove double matches against the same team because they skew the results a little bit as well. Effectively the increase the weight of one team. A team getting 4-0'd by the Titans twice isn't any weaker than a team that plays the Titans only once and gets an easy win against a bottom team, yet in the SoS they will be rated as such. Even if you don't want to go into the whole mess of "opponents' opponents' record" because that's to close to rating the teams instead of the schedule, always resutling in "hard" schedules for bad teams and vice versa, double matches with the same result should be counted only once.
This would push the teams where you'd expect it even close to 0.500, but I don't have the time for that and just addressing the elephant in the room, the 14% of the SoS that each team generates themselves, already paints a far more accurate picture.
1: Seoul Dynasty (.607), Stage 1: 22-20, Stage 2: 29-13
T2: Boston Uprising (.595), Stage 1: 24-18, Stage 2: 26-16
T2: Los Angeles Valiant (.595), Stage 1: 26-16, Stage 2: 24-18
T4: San Francisco Shock (.548), Stage 1: 25-17, Stage 2: 21-21
T4: Chengdu Hunters (.548), Stage 1: 23-19, Stage 2: 23-19
T4: Guangzhou Charge (.548), Stage 1: 21-21, Stage 2: 25-17
7: Toronto Defiant (.536), Stage 1: 22-20, Stage 2: 23-19
T8: Shanghai Dragons (.512), Stage 1: 24-18, Stage 2: 19-23
T8: Houston Outlaws (.512), Stage 1: 20-22, Stage 2: 23-19
10: Hangzhou Spark (.500), Stage 1: 17-25, Stage 2: 25-17
T11: Atlanta Reign (.488), Stage 1: 20-22, Stage 2: 21-21
T11: Florida Mayhem (.488), Stage 1: 17-25, Stage 2: 24-18
T13: Vancouver Titans (.476), Stage 1: 19-23, Stage 2: 21-21
T13: Paris Eternal (.476), Stage 1: 23-19, Stage 2: 17-25
T15: Dallas Fuel (.452), Stage 1: 23-19, Stage 2: 15-27
T15: Washington Justice (.452), Stage 1: 21-21, Stage 2: 17-25
17: Los Angeles Gladiators (.440), Stage 1: 20-22, Stage 2: 17-25
18: New York Excelsior (.429), Stage 1: 21-21, Stage 2: 15-27
19: Philadelphia Fusion (.417), Stage 1: 14-28, Stage 2: 21-21
20: London Spitfire (.369), Stage 1: 18-24, Stage 2: 13-29
As you can see a few things stay the same.
E.g. Seoul did have a very difficult schedule (in fact the most difficult), London had a ridiculously easy schedule, New York had the easiest (although not outrageously so) and San Francisco had the hardest schedule out of the top 3 teams, Washington and Shanghai achieved their first win and first playoff appearance respectively in their easier stage.
But the margins changed and some things even reversed themselves. SF actually got a fairly hard schedule instead of 0.500 and their perfect stage was decidedly not against a particularly weak SoS. However Vancouver Titans' was also fairly even instead of the easy road that the SoS suggested without the adjustment.
So the good teams didn't have it as easy as it seemed. On the other hand, boy do the bad teams drop. The Houston Outlaws and Florida Mayhem did not have difficult schedules. They were very close to 0.500, they just sucked. Even worse the Washington Justice drop from 0.510 to 0.452, quite an easy schedule. Their only win happened during the 4th easiest stage 2 schedule, only beaten by the NYXL (making their decline in stage 2 even worse), Dallas and the perpetually lucky London.