Why has he gone out of fashion? Just played vs 1 that just tanked and taunted everything like there's no tomorrow.

He (Hormel Chavez) ended up going 19/8/20 and was simply impossible to deal with. And looking through the guy's Rammus games in the past several weeks and the w/l percentage and k/d/a stats derived from playing him...why is he no longer insta-ban in tourneys or even in draft games ~2 months ago?

Because cheese is only fun for so long.

1. As BeefJerkyHunter wrote, many players find playing him boring.
2. Many people who've played Rammus used to backdoor a lot. Backdooring became less effective.
3. As people tend to travel more together, being a single target CC only tank, with only the 1 CC, made people prefer other tanks over Rammus.

People prefer tanks that have more utility and more damage like Blitz and Maokai.

Removal of Priscilla's Blessing contributed to this. I think also people started figuring out that having a roamer on your own team effectively negates the contribution of a character who mostly spends their time back-capping.

He's really good at catching people off guard or alone, but at higher levels of play that happens less often. Though I do believe Aesh plays a fearsome Rammus and has had it banned against him.

He's no longer insta-ban unless someone is extremely good with him.

1.) He's not boring, rather he can really **** over players by sticking to them/being a disruption. Most people would rather not think outside of the 4-top/1-bot meta, and champions like Rammus force you to think harder if a skilled one can tank, taunt, and POOTERSS around all at once. I just got cursed out for it yesterday Veni, right before my match with you, lol. He's boring when people can't faceroll (guess who stated he was? A Jayce player, and a Pantheon)

2.)If people are smart, the ideal thing to do is focus him, especially early game. If he starts building resistances, well focus the damage dealers he's protecting or get LW/Void Staff (Because I can't stress enough how derpish people are when they continue to build damage and very little armor penetration)

3.) Rammus can be dealt with if he decides to go backdooring. All it requires is a little more map awareness.

Essentially, Rammus is only a pubstomping champ. He's a real feat to play once you take on stronger peeps, and if you're good with him in tourneys, they will ban him. Have no fear.