More than likely they just used a pile of shards to get those. Less luck, more money.

with the odds of 0.5% it's over 300 shards in less than 3 minutes 

maybe you are correct 

0.5% if he was pulling blue shards, 6% chance if he was pulling yellows, with mercy starting after 12 pulls.

6% for sacreds. Could have popped 20 for summon rush

A couple things:

1. Belz was a Fragment summon so it's possible they just never pulled him and held them for a couple months till this Fusion and pulled it thinking it would give them points

2. What everyone has been saying about Sacreds is the most likely. I pulled 5 sacreds and got 2 Legendaries (which is VERY unusual luck for me) last night. 

Also to your question about odds, I can tell you that even I thought at one point that the pulling system was rigged but the math is actually correct. If the sacred chance was 5%, 3 in a row is a chance of 1 in 8000. Since it's a 6% chance it's better than that and that's the statistics of doing it in a ROW multiple times. The odds get better if you're pulling 10 times. Since this is a game with a estimated average of 2 million players, it's not super unlikely to see that happen in chat.