is it really impossible to climb out of silver using only vel koz?

ive recently just relapsed back to league again after a couple of years. Now with a new acc along with the new season. Ive played about almost 50 games and ive trying to one trick vel koz and been using him either mid or support. In most cases of my game (mid) i always try to quickly clear the wave in order to look for a play in other lanes and it works. I get kills, i help my team get kills and objs. But I just cant seem to win, we usually have the early lead but lose it towards the end of the game. ive been shotcalling my team on what to do and it works...... sometimes. I know im not the best, but why is it so hard to win games in silver? back in 2018 i hit my peak(plat 1) and ive always found matches back then fun. But now i just cant get out of silver and it sucks. I usually win lane too but its just so hard to win. So should i just stop picking vel koz? Sorry for the long type im just frustrated.