Eric traded minor pieces with his opponent, maintaining material parity, but eventually deadlocked. While one of them might have had a theoretical advantage, they’d have probably run afoul of the fifty move rule trying to exploit it, so a draw was agreed.
Dave’s opponent castled first, kingside. After some tense manoeuvring they ended up with a rook and four pawns each, then quickly agreed a draw.
Robert made some questionable moves early on, but won a knight with a fork, and kept this material advantage throughout the game, ending up with a rook, bishop and two pawns against just a rook and two pawns. He also had an extra fifteen minutes on the clock. A draw might still have been achievable for Alex, but then he lost his rook and resigned.