I am not sure if the odds are adjusted based on the probabilities before the match and during the match. It is true that when the match is ongoing, we will see the odds being adjusted according to the real situation of the match. But there are definitely factors where the bets placed influence the bookmakers in adjusting the odds. I don't pay much attention to this, because I more often bet before the match and then just leave it be.
I also don't focus on the odds before betting and this is especially because I bet even before the game
startstarts and during that time you don't have such fluctuation.
Such fluctuation happens mostly when the kick off is near as bettors emotion begins to reflect on the picks or if there are late biase and news from the team camp or if there are speculation of match fixing.
I follow stats more than odds because to me, odds doesn't reflect the possibilities in the game. Take for instance, why will a team with high odd like 7 odd defeat team that was given 1:40 odds, you see it doesn't reflect the real score. So instead of fixing your eyes on odds, I do more of analysis, checking on injuries, team spirit and using the prediction sites.