Yes he's strong, but at 18. He still hasn't developed his "man strength" yet. Right now he's holding his own. By the time he's 21 or 22 years old. Is when you'll truly start to notice his true strength. If for example, you had Xhekaj and Slafkovsky playfully wrestle. Even though they're about the same size. My guess is for now, Xhekaj would throw him around like a rag doll.
Up until pre-covid. I used to work with OPP cadets, training them in self-defense. In my late 40's, at 5'7 and around 210lbs. I could easily toss around guys (18-20 years old) some were almost a foot taller and weighed 20 sometimes 30lbs more than I did. Once these guys became older. I was no longer able to overpower them.