With glimpses of old Indian bad habits coming to the fore, Oltmans feels it will be a concern if this form continues throughout the tournament.
"The team stuck to their gameplan till the last minute today", the Dutchman, who is also the High Performance Director of Indian hockey, said at the post-match press conference.
“We have indeed improved, but you never know how much unless you play the best teams in the tournament”, he said.
The first of India's only four shots at goal came in the 26th minute.
"We went back and back and failed to go forward. I am happy with the overall performance, but of course there is always room for improvement and that's what we will try to find out", he continued.
“For me, the result is not important, what is important is performance and today our performance was by far below the level”.
After the match, Oltmans had to admit it was "a disappointing game" where the players "tried less ahead from the second quarter onwards but not enough to worry Argentina".
Speaking about the defeat against Australia in test series, Raghunath said that victory and defeat are part of the competition and the team is taking it in a sporting manner.
Oltmans said India showed intent and created more chances today, which was not there in yesterday's game. "In 24 hours we play Germany, another tough match".
Going by the world rankings, it is expected to be a close duel as India are just place one rung below Argentina (5).
India will take on defending champions Netherlands in their last Pool B match on Monday.