well hangar show down by sp would make you more problems than solutions, sp droppers would be abusing it exactly as they do normal matches. Even now there are players with only 4 mechs in HS, because they hope that they will win before 5th match begins if they put stronger robots in first 4 while going down a league.
They could have separate win % rate for HS for players for each league (so for example if you won 70% in league 3 and you coming to league 2 your win % would start at unknown value or neutral 50%, so if you switching back to league 3 then you back to your 70%). And from that win rate they could group players in teams accordingly so its impossible to have two players with 90% win rate against two players with 10% win rate.. it would be humiliation/domination scenario. The aim would be to group 10+90 vs 10+90 so its challenge for both teams.
But nobody is here to listen about our opinions