Koeman pleased with point at Ajax
Teenage defender Stefan de Vrij had given the visitors a 61st-minute lead at the Amsterdam ArenA but they could not add to their lead, despite the dismissal of home goalkeeper Kenneth Vermeer, and Jan Vertonghen headed the equaliser for ten-man Ajax.
Koeman nevertheless declared himself more than satisfied with his team's progress this term after their tenth-placed finish last season.
"I hope we can keep this up," he told the club's website. "We are doing far better than I expected. After the game against AZ, we were disappointed that we did not at least get a point, but today we felt that we could and should have won.
"We have shown in games that we can play with guts. If we continue to develop in this way, we can maintain our position in the standings and push on."
The former Netherlands international admitted, though, that his side's form had dipped in the final half-hour. "In the last stage we did not play well," he added. "We were sloppy, played the long ball too much and lost duels that in the first hour we often won."
The draw left fourth-spotted Feyenoord seven points behind leaders AZ Alkmaar - one point and two places better off than the Amsterdammers - after ten games.
De Boer unhappy
Ajax coach Frank de Boer suggested his team were feeling the after-effects of Tuesday's UEFA Champions League win over Dinamo Zagreb in Croatia, and was far from happy with their display.
"Feyenoord played well and we were slack," he told NOS. "It appears to be a trend that we have great trouble recharging our battery after a European match. And why was there only aggression from the team after the red card?
"We performed below par as a team and lost the ball carelessly a lot. We have picked up too few points. That must change now."