Can you really become a class A player by studying tactics?

I am like class G

+1

Don't allow the trolls nonsence to reign free

That was 15 months ago.

I'm guessing you've improved your record against players rated +1800. How are things going?

Class A players know very little strategy. Tactics will get you to about expert level but you need to be diligent.

I actually know John Coffey, the person the OP talked about. When I met him in 2012 he was a strong Class A player. We've talked abot what he did to improve and he did a lot more than just tactics.

He walked a lot on opening preparation. He played certain openings and everyone knew it (French Def, Nimzo Indian, d4 & c4 & Nf3 with white). Personally it was easy for me to get him out of preparation. I remember once where I beat him as White in the French but using a crushing tactic that led to a dominating position with two pawns up. What did he do afterward? He literally played dozens and doezens of blitz games with his buddies on the variation we played. 

Coffey considers himself a good endgame player. He studies a lot of endgame puzzles. I recall one tournament he was playing an 1800 player who abruptly resigned as soon as the endgame appeared. Puzzled, I asked Coffey why his opponent resigned. Coffey shrugged and said: "He probably heard about my legendary endgame skills." I have no idea if that's why his opponent resigned but Coffey studied and valued his endgame knowledge.

Our last regular rated over the board came in November 2014. I was Black and a bit surprised he opened with the English (he almost exclusively played d4 at the time). It transposed to a Panno variation of the King's Indian Defense which I was very comfortable in. Our battle was a tense one full of tactics and calculation. I was better out of the opening, won an exchange due to tactics (though honestly I could've won a whole rook), and we came down to an endgame where I had my rooks on the seventh (or second since I was black) but he had a dangerous passed pawn. It would have been a long struggle where I should be winning but BAM - he blundered but it wasn't so obvious why. He sacrificed his knight and thought he could queen his pawn but missed a pretty endgame tactic where I stop his pawn while being up a rook, or I mate him. 

The point of all this is to illustrate that John Coffey didn't make it to Class A just studying tactics. He spent much time on studying and memorizing openings and improving endgame knowledge. It was a combination of things that took him to be the strong Expert player that he is today.

I do think Coffey has weaknesses he can improve upon. He's not as strong in tactics as he thinks he is. Calculating wasn't his strong point and he ought to work on that. You can check out his blog at http://chessplayeratlarge.blogspot.com/ and see his lastest games. His last tournament he was bascially gifted two wins and won a game he should have lost. It takes much more than tactics to hit Class A and beyond - just don't ask John Coffey.

Meh, players can surprise you. Some are complete fools in endgames, or when they have the initiative, or when they have to defend, etc. There's something they're bad at or ignorant of, but it's not necessarily strategy.

And sometimes even when they say they're bad at ____ or don't study ____ they do a lot better than their peers at ____

It helps to actually look at a bunch of openings and positions with well-known pawn sacrifice gambits in return for open attacking lines. Two of the best ones are the Evans Gambit and the Smith Morra Gambit - they're' so dangerous that GMs regularly go down against these lines if they accept the pawn. Neither of these gambits offers a definite tactical win, and many refutations have been 'tried', but none have been proven to be absolute. 

It also helps to intentionally play gambit openings for awhile until you get a sense of how to sacrifice pawns or material for a better attack. 

Of course, studying tactics is the most critical and fundamental way as well - your tactical problems should have quite an abundance of material sacrifices for checkmates or to win back even more material. These are more concrete wins than the unclear gambits listed above, but the ideas hugely overlap. 

I hope I will not become class A player by solving ChessTempo (and other) tactical stuff :P

It's easier to be well rounded, but you can of course have a very aggressive, tactical, style and get by with minimal knowledge in everything else. There are some players who seek to create, before move 20, a decisive advantage (for them or their opponent!) in every game for example.

The question becomes: what's the minimum for "everything else?" 

Most curious people, who don't dislike learning something new or changing their habits, will pick up the minimums on experience alone (after some years).

It's a misnomer to say "only tactics," but to some people that's how they may perceive it.

Talking about dropping down to below your masterlevel? Play bullet all the time. Let the bad habits and wreckless calculation become your normal way. Then you will experience that it takes very much selfcontrol to slow down and avoid making sloppy calculated moves in longchess. 

This was unexpected.

Not everything, but an essential foundation. Tactical awareness will help you make use of strategical opportunities.

I accept bets about the new handle GreedyYuriThessa will use (until he is banned again, that is).

I got to USCF A Class without much tactics study.  I have always really enjoyed studying middle, and endgames.  I have had players tell me that i blunt what thye are trying to do "tactically".  Do i always see what im doing to cause that? Nope...Studying Petrosians games have really helped.

I am trying to improve, and believe strongly that for me all kinds of chesstraining helps, including tactics. Last week I have been watching several videos from the candidates matches, commented by GM´s like Daniel King and Jan Gustavsson. I hope and thinks it helps.

I do not think that I that is more than 50 years old ever can reach a-level studying only tactics. I need to work on more than that. If I ever get there isnt clear.  The climb from 1437 FIDE is long and difficult.

Magnus Carlsen's AMA on reddit is an eye opener.A better question should be what is the best way to learn tactics.

I've found that doing something outside of your comfort zone for a while usually yields new insights. If you've hit a wall, try picking something that people often recommend, something that doesn't sound fun to you, and do that every day for a while.

That's why I stick forks in my eyeballs.