Blue lives matter is a troll of black lives matter. Police chose to be police and a large portion of the criticism of the institution of policing is valid and didn't form out of a vortex. I don't for a moment believe "blue lives matter" was created in good faith. They're also unique in that they carry guns and can detain people so they're understandably held to a high standard. That's not remotely comparable to a minority of the population who has suffered every imaginable human rights abuse and indignity this side of Nazi Germany (who took inspiration from Jim Crowe laws btw, isn't that fucking wonderful) and until only very recently could be openly and legally discriminated against, and the police upheld the state's laws that oppressed them and in some areas the police were originally slave patrols (makes the term "patrolman" have a different ring, eh?). Once they were sorta on paper "free" they continued to get the middle finger from the country that benefitted from their labor while getting no restitution.
With the police, we're speaking of an institution, your comparison to MMA isn't relevant on any level. That doesn't mean every cop is a piece of shit nor that they do nothing good for communities, any reasonable person even if they disagree with the institution (on whatever level) would agree that there's good cops that do good work. I don't know what percentage of police are "bad apples" but clearly enough to be a problem and to question the structure of the institution, particularly in the US.
To use your apple analogy, I'm sure that depends on department among other factors. If you have an apple that is rotten (or more than one) or the way you store them causes rot and you're aware of this and little changes... that's a problem. A problem with a badge and a gun.
In any event, my rambles aside, there's probably good FBI and ATF agents - where's their movements? What colors should be associated with them? Feel me?