This start makes me remembering two seasons ago when Barcelona won La Liga with very good defense. It seems they are trying to repeat it in first three matches and if they can maintain good defense in rest of season, chance for them to win La Liga is high enough.
I think the top 5 positions in Laliga this season will again be filled by teams like Barcelona, Atletico, Real Madrid, Bilbao and Girona. However, it turns out that this is not happening at this time. Maybe because this is only week 3, there are certainly still many teams in Laliga that have not shown their best performance.
Real Madrid let Barcelona expands the gap after only three first match days but they surely will try to improve, play better and catch Barcelona in coming weeks. Two main competitors for La Liga title will be Barcelona and Real Madrid as other clubs don't have enough good resources to fight for a league title throughout a long season.
Apart from that, the current top scorer in Laliga is Lewandowski with 3 goals and in 2nd place is Oscar Mingueza from Celta Vigo. I think with these results, it looks like Lewandowski will show his best performance again this season. Even though he is quite old now, Lewandowski is really no less competitive than the other strikers in Laliga.
Opportunity to win La Liga for Barcelona will depend on their defense system that seems operating well now and their main striker Lewandowski. If he can contribute many goals for the team, Barcelona will have better chance to be a champion of La Liga again. It can be a last chance for Lewandowski to win Pinicchi award in La Liga because he is old enough and does not have many time to play at highest level.