Yes. They have some matchmaking based on skill. As you win more matches, you rank up. If you lose them, you lose rank. Each tier group is a different set of player skills. You were winning more often because you were better than the players you were facing. Now that you've went up a rank, you are facing more skillful players. If their skill level is too much higher, you'll eventually fall back down to the high end of the lower rank you were just at

@SilverBride there is a good addon called "Tribute Improved Leaderboard" at ESOUI
It works only for Rubedite tier, though

Ranking is made quite crazy. Many times i get zero points for winning the game and instead advancing i desend in ranks. This is a complete madness. Also, it is totally unclear how this ranking system works. You may lose -1000 points for a single loss (can you imagine Magnus Carlsen ELO drops from 2864 downto 1500 because of a single loss? that is exactly what is happening with ToT rankings).

I strongly hope developers could fix this strangely working system. Or, at the very least explain how it does work?

[snip]

Now, if you'll excuse me, I would recommend watching Revalia's each of 8 desks analysis
https://www.youtube.com/user/pseudosupport/videos
Pink Apple also has reviewed 4 starters desks
https://www.youtube.com/channel/UCFjf09OYvVLPuxrloMRUpmg/videos
Some of theirs evaluation could be debatable, but on the overall these tutorials help to establish a good priorities system
(what cards you would like to buy first (and also - what discard from the Tavern to avoid your opponent buying any good card))
Also there is a good strategies video from Old Salty Sean https://www.youtube.com/watch?v=B3wcgXpONv4

Practice & self-confidence do the rest of the job.
Good luck.

[edited for baiting]

@merik1999 @DinoZavr They are not talking about the rank points in Rubedite. They are referring to the fixed 110,210,310 points you get in the lower tiers.

ZOS should allow deranking (let players obtain the rewards for their peak tier that season) to allow for better matchmaking. With a 50% winrate, every player will slowly float upwards since they get at least nett +10 points for every win/loss. This inevitably leads to players being matchmade against others above their actual skill level, and ruins their game experience.

If allowing deranking opens up the system to exploitation, perhaps you should still not be able to derank from Rubedite. Alternatively, the points from wins and losses need to be equalized so that you need a positive winrate to move up a tier.