Brrip mkv too highly compressed?

[SoShy]

Hello, not sure right forum but got little problems with bluray playback.

First whatever.720p.BRRip.x264.AC3-xxx.mkv 2.18GB
Second whaterver.720p.BRRip.XviD.AC3-xxx..avi 2.98GB
Third xxx720-whaterver.mkv 4.36 GB

The Bluray player supports 1080p .MKV
The first .mkv file will strictly not play
The second.avi will do just amazing, but the file is also a bit bigger (not alot, but its a difference)

Ive been trying to figure out what to do but I just can't understand.
So far as I follow is because the first .mkv so extremely compressed so thats why it cant be played on the bluray player?
Because the third is a "real" HD movie and works alot better, could it be like that?
Tryed to do a Mux with mkvmerge, dont even know that it means, but didnt work.
Reading at http://www.matroska.org/news/compressed-headers.html but dont get smarter..
What am I doing wrong and how can I make the smaller .Mkv work as good as the .avi ??
Appreciate any help

[Baldrick]

File names and sizes doesn't say anything. Compare the video and audio codecs with mediainfo.

But as BRips are probably warez download then I'm closing this thread. Just buy the blu-ray and rip. You have full control then.