They were able to beat strong teams before their winning streak was snapped. If we go back to their record, we can see they beat the Sixers, Bucks and Denver. Winning against the Denver which is a defending champion is already enough to conclude that they are a strong team, although young and lack of experience. A lost of OKC should not be a factor to conclude that they have no chance in the playoffs, this team are playing good basketball, everyone in the team are ccontributing, so let's be optimistic with this team.
The performances of teams like the Thunder and Timberwolves are impressive this regular season. Honestly, I'm still not used to seeing these two teams at the top of the standings.
However, it is worth keeping in mind that a good performance by any NBA team throughout the regular season doesn't guarantee that a team will succeed in the playoffs. A prime example of this is the Suns in the 21/22 season.