This is actually something that can be considered as luck or not, because there are several reasons why things like this happen.
I'll start by saying it's not luck, like if they had played better than the rest of the club, then they would have been the best. But if we attribute it to luck, then there is a connection. For example, last season they did well from the start of the season, and they even held first place for a very long time. But towards the end they weren't consistent enough, and unfortunately there were clubs that were more consistent than them.

As I said at the beginning, when talking about this there are certainly things that will then be very related, including luck. We can't deny that it does exist in the world of football.