GLORY Lightweight Champion has been training in Mixed Martial Arts for a while now, that much has been widely reported throughout the MMA blogsphere as when it comes time to talk about an MMA fighter's credentials, saying stuff like "training with a killer kickboxing champion" makes for an interesting story (while actually covering kickboxing does not, apparently). So we've known for a while that van Roosmalen has been training in Florida with sights set on taking the journey that many other kickboxing champions have made by wading into the pool of Mixed Martial Arts.
The result was a positive one for van Roosmalen, although it's fair to note that he did look a bit rough in the grappling department as many high level kickboxers tend to look when they work their way into MMA. Unlike someone like Verhoeven who fights in the less talent-rich heavyweight division and could have a greater deal of success with less refinement, van Roosmalen chose to cut weight down to Featherweight for his MMA debut. Featherweight and Lightweight, the two divisions that he'd be competing in, tend to be more talent rich and full of talent all throughout the world and the grappling of a 6-5 fighter in Anthinodoros Michailidis gave him some serious trouble in the opening round.
That doesn't mean that there isn't room for improvement, but it's difficult to see such a talented champion like him struggle like that, especially with kickboxing's at times tenuous grasp on convincing hardcore fans that this current crop of fighters is as elite as the previous generation.