Ossasuna is not really "that" great, yeah this game looked close but it is not really that close and this was looking close for one reason because Real Madrid missed many chances. If half of the easy chances converted, the game would have been 5-0. Not saying all their shots, literally just half of their chances.
In any case, I think it's close to what we are facing right now and that is why I think Ossasuna could be just a midtable team and nothing more. That isn't bad though, I mean they should be happy because they are spending midtable team money to players and everyone, so they end up where they deserve. Being worse than what you deserve is a worse situation, so being where they deserve is actually good in football world because you get what you expected.
Not only did Real Madrid miss many chances, but their performance was less than impressive, despite Osasuna's defensive strategy. Xabi Alonso should have been able to do more with the players they had, but in reality, Xabi Alonso's strategy was quite monotonous from the start.
However, Osasuna can't be judged on anything. It was a first-week match, and we can't judge a team's strength just from their first match. Although Osasuna are a mid-table team overall, as was evident last season, we also have to realistically assess their strength compared to Real Madrid, and the difference is vast.