Black's choice of playing ...c6 instead of ...Nc6 allows him to better fight for the d5 square, always a key one for the English. The drawback is that the pawn on c6 gives White a target for his b4-b5 queenside push. The early middlegame is always a critical time in these types of positions, as White can either gain the initiative on the queenside, or cede it to Black in the center or kingside, depending on who uses their initial moves most effectively.
In this game, White waits too long for the key b5 push, then when he does make it, it is (ironically enough) insufficiently prepared due to Black's threats on the long diagonal. By move 16, Black has largely defused White's threats on the queenside and opened the key e-file. However, he then exchanges away his beautiful Bg7 and White is perhaps slightly better afterwards. White fails to see some complicated tactical possibilities on move 22 and the position then is equal.
What happens on move 24 is very instructive. White goes for a cheap threat pinning the Nc5 to the queen without bothering to calculate Black's response (...Qd5+), which is an example of failing to see the opponent's Checks, Captures and Threats (CCT). Black's check immediately frees him up to take advantage of the ...Nd3 fork threat, which White completely misses, although there was still a defense. Once Black goes up the exchange, the game is won.
In this game, I failed to appreciate the significance of Black's central counterplay, both originally with his 14...e4 push uncovering the attack on the Nc3 (although I had seen the threat) and then with the ...Nd3 fork and queen maneuver (which I completely missed). The analysis of this game should help me increase the necessary sense of danger in such situations.