Clasie has seen his initial time at St. Mary’s disrupted after he picked up an injury soon after arriving in the summer.
And he is yet to play 90 minutes in a league match, with Koeman feeling that he still needs to adapt to playing in English football.
“He’s not the physical, most strongest player and that’s the reason I change Jordy after 70 minutes [against Bournemouth] because he needs to learn and to adapt to the Premier League and we give the boy that time,” Koeman explained.
“He showed his qualities and he will learn and adapt to the intensity of the Premier League.
“He has big qualities in his ball possession.”
Clasie is expected to have a big part to play for Southampton this season, and Koeman has brought him straight into the side’s starting line-up upon his return to fitness.
The 24-year-old has started the Saints’ last two matches, and he is likely to remain in their team for their upcoming clash against Sunderland.
Southampton are without Victor Wanyama at the weekend, meaning that Clasie is expected to be part of the Saints' line-up for the foreseeable future.
If Southampton are able to beat Sunderland at the weekend, they could move up as high as fifth in the Premier League table, after making an impressive start to their campaign, and they will hope further improvement from the likes of Clasie continues to carry them forward over the coming weeks.