ping is not a constant number, it is just a measure of the round trip time (in miliseconds) of sending a packet from you to a server and back.

its absolutely pointless doing a pingtest for anything game related as the number it produces is pointless and only applies to the device you pinged from in this case your pc.. the only useful data it can give you is the amount of jitter on long distance pings and whether you get much packet loss, but again these are pretty pointless when it comes to games as games use udp packets not tcp/ip which pingtests measure.

you arent actually being put into 75-100-125 games the way match making works is each step it just broadens the range of pings to search

so it goes 0-50 then 0-100 then 0-125  ect  so just because search is saying its now looking for 125ms games means you could be placed in anything from 0-125ms lobbies.

Might have something to do with the fact that when it scans for games it starts finding acceptable games under 50 ping (i.e. 15/50), then the number of games found automatically jumps back to 0 before its done searching. 

Matchmaking is just garbage.