Jonathan Pein FM

Overview

Jonathan Pein, better known to opponents as McCarthyStone, is a FIDE Master who has turned online blitz into an art form. Since first appearing in April 2020, he has played more than 8,000 rated games of blitz and bullet chess, peaking at a blistering 2676 (2026-09-03) in blitz and 2793 in bullet. The username sounds like a firm of British estate agents. The chess is considerably less polite.

The 2020 Breakout

Pein debuted in the spring of 2020 rated a modest 1959 at blitz. Within a single month he had cleared 2400, and by that summer he was flirting with 2500 while most of the world was still perfecting sourdough starters. What followed was six years of steady, stubborn climbing, with the curve finally cresting above 2600 in 2026.

The b3 Manifesto

Every online grinder has a calling card, and Pein's is the Nimzo-Larsen Attack. He has opened with 1.b3 in over 800 bullet games alone, scoring a healthy 56%, and in 2025 he pushed the b-pawn a staggering 545 times. Opponents expecting 1.e4 are routinely treated to a flank attack and an existential crisis.

The repertoire does not stop there. His toolkit includes:

• The cheeky Amar Gambit, a bullet weapon with a 59% win rate that has no business working as often as it does
• Offbeat Colle lines for opponents who like quiet lives, preferably theirs
• As Black, the dependable Philidor Defense, nearly 300 blitz games of it
• A Caro-Kann Defense that wins an absurd 73% of his blitz games

Foes and Feuds

Pein's most-played opponents read like a rogue's gallery of online warfare. His record against vavom2 is a flawless 23 wins, zero losses, which is either dominance or a hostage situation. aattack12345 has managed one win in 32 tries, while kareembenzema has endured 35 battles for a respectful but bruised 23-3-9 ledger. Every hero needs a nemesis, and Pein's is LadyCockroach, who leads their head-to-head 18 to 12 and presumably never lets him forget it.

Quirks and Fun Facts

• Longest winning streak: 19 games. Longest losing streak: only 10, and he sulked about it for a full hour.
• Peak performance window: 2 AM. Sunday is his best day at 57%, Wednesday his kryptonite at 48%.
• Early resignation rate under 2%, paired with an 83% comeback rate. He does not lose positions, he renovates them.
• Over 9,000 queen checks delivered. Subtlety is for the well-rested.
• Average winning game lasts 78 moves with the first capture around move 7, making him a patient endgame grinder despite the speed chess facade.
• A tilt factor of 10 out of 100. The Stone in McCarthyStone is load-bearing.

Legacy

Whether he is wheeler-dealing a Nimzo-Larsen at three in the morning or squeezing water from a rook endgame in a 78-move blitz epic, Jonathan Pein represents the modern online chess hobbyist taken to its logical extreme: vast, quirky, resilient, and quietly very good. Would-be challengers are advised to avoid Wednesdays, bring a plan against b3, and ideally be someone other than vavom2.