a player rated 689 but 98% accuracy?!

I was playing a game with this guy  https://www.chess.com/live/game/5973410878

A report of it said "Tough game. Your opponent played well"..

But look how well. It says 98.5 accuracy. That doesn't seem normal to me.  The system matches me to players at a similar level to me.  No opponent i've played has ever played with accuracy that high.

I only blundered once (though granted it was a huge blunder, I lost my queen).

He played 15 games in one day that looks suspicious.  A human brain working alone would exhaust themselves with that many games.

Here he had an accuracy of 1.9 https://www.chess.com/analysis/game/live/5976488037

Here he blundered 10 times with a 43 accuracy https://www.chess.com/analysis/game/live/5977260878?tab=report 

So he seems to be either way too good, or very mediocre for his rating, or terrible.

Definitely the 98 accuracy seems very suspicious to me.  And not consistent with sometimes in some games getting low accuracy / low accuracy and 10 blunders.

Anyone can get 98% accuracy if the game is not very long

I had a quick look at the game. Many of the moves looked like simple and logical choices. Pawn pushes attacking your pieces with tempo, good use of weak squares, nice discovered check and picked up your rook. Some simple and effective tactics. Nothing obscure. Maybe he just had a great game.

oof

Okay, interesting.. I was focussing on not blundering.. as in a previous game where I asked a question here, it was suggested that I should focus on that.. And I have been winning more games since then..  ( did end up blundering losing the queen. But that aside..

Where was I going wrong here / where could I have improved?

Thanks

well f7-f5 wasnt a good idea given the position. Your opponent won a bishop and rook for a knight with a discovered check. But more strategically I'd say you failed to fight for your fair share of the centre. Your opponent was able to build up a strong pawn centre with his pieces around it. He had good centralisation. This was helped by you hanging your e5 pawn in the opening. 2...Nc6 would have supported e5. Google Guicio Piano and look at both sides and understand the reasons for the moves.

On the blundering. I don't think advice to not blunder is helpful. It doesn't tell you what to do. The skills you need to develop are calculation and visualisation. Blundering is a sign that these are weak which is normal for beginners. They can be strengthened by regularly doing puzzles which also develops your tactical knowledge. The puzzle engine and lessons on here will help, a good book is chess tactics for students by Bains. Give it time (months) and, combined with some more experience and knowledge) you will naturally calculate more and consequently blunder less.

Giving up material to a discovered attack is a blunder. 

The description of the game included a discovered attack.

13.Nxb6+ is a discovered attack also called a discovered check because in this case it was an attack on the king. The check gave your opponent an extra tempo (move) because you had to move your king. This meant you couldn't recapture which allowed them to then pick up your rook. It was a tactical blunder as the threat was foreseeable but you played f7-f5 and blundered into it.

At his level he can win more games with this essential skill...

Stop giving away your pieces and take the pieces that have been offered to you.

Then you will need to learn many other things. I think that is why puzzles are so important. They teach many things, including identifying targets, potential pieces you can win.

I often play more than 15 games in a day without being tired so wouldn't call it suspicious

Ok. I've cleaned the kitchen floor, had a cup of tea, and had a think. This is why I like Daily. You've blundered your e-pawn. Dont panic! You just need a plan. Plans are great. They unify moves. I reckon you haven't lost a pawn, rather gained a half open file in front of your opponents king. Try to open it. The target of the plan is e4. Your first job is 3...d6 to kick the knight out, then look at Nf6, o-o and e8 to put pressure on e4, if Nc3 or Nbd2 then try to exchange it off for your dark square bishop (remove the defender). b6 or b5 followed by Bb7 brings another attacker to the party. Nc6 can be used to control e5, blockading the pawn. If d3, then try to exchange for your c-pawn possibly supported by the b-pawn. Some of this may not be possible depending on your opponents moves, but you get the idea. You are looking to try and win e4 or prevent your opponent from dominating the centre by forcing them into a more passive position defending e4. Planning is key. It's difficult as a beginner as planning wont help you win games if you blunder material, but you know this, so I thought I'd offer something different.

Can't express this enough...

A HIGH ACCURCY RATE BY YOUR OPPONENT MEANS YOU PLAYED WITH ERRORS!

SAME GOES FOR YOU HAVING A HIGH ACCURACY RATE!!!!! (MEANS YOUR OPPONENT PLAYED WITH MORE ERRORS THAN YOU. ) Gm's playing each other have accuracy rates usually in 80% .. the measurement is not a strength indicator 

MY BEST GAMES, MY TOUGHEST WINS... and losses My opponent and I both had accuracy rates in the mid 80%. (meant we were equally matched... )

I played 100 the other day. We played some book openings in the London, I played 3 moves out of book, the other guy hung their queen and resigned. It was a short game and I was playing a trap line I learned. I am a 900 Elo in blitz. Just because my Elo is low, doesn't mean I will play every game like a potatoe. Same with everyone else at low Elo. We are all random blunder generators, but we do know some theory in opening, middle and end games. We do spot tactics when we lock in. We are low Elo because our autopilot habits are bad. High accuracy is possible at any Elo when the other side craps the bed.