How much is the decrease in power? is it between 1-5 bp difference?

When you switch team, gears can reorganise themselves. For example, lets say your main isn't wearing the beast gears, you gave them to other ninjas in your team in accordance to their strength/weaknesses.
Now lets say, during nine tail event you remove all ninjas and then put back others.During this, your best gears will shift to your main. When you put back your team later, due to mixing gears it may have very slight increase/decrease(generally between 1-5 power score). This is normal, no need to worry. Just put those gears back manually to where they were before and all will be good.