We live in a world of probabilities, not certainties.

I guarantee that if people play the "best runner" they are going to get hammered. (Assuming they play more than some tiny percentage of races.) There is NOTHING that says the best runner owes you a profit. And people that spend their precious time trying to distinguish which of the top two or three is REALLY the best are just wasting that time.

At Melb dog track the 2-1 favorite coming out of the #5 box has an average ROI of -9.02%. And, a 2-1 favorite coming out of the #8 box has an average ROI of -33.46%. So, on average, your 2-1 favorite starting from the #5 box is worth 91 cents for every dollar you play on him. Put the same dog with the same odds in #8, and now he's worth less than 67 cents per dollar wagered!
Within a percentage point or two, the 2-1 favorites in #5 and #8 will actually win just about the same number of times.
But the crowd ALWAYS OVERPLAYS THE #8 BOX AND ALWAYS UNDERPLAYS THE #5 BOX! If you do your handicap, and get the same strength of winner in #5 and #8, you SHOULD NOT PLAY HIM THE SAME WAY FROM BOTH BOXES! If you do, you're being a fool. That is why I chide those who do their handicap, and then get up and play their favorite in the same kind of wager, no matter what kind of race it is, and no matter what box their dog is in. They spend all that time finding a favorite, then they likely throw away whatever advantage they might have by making a stupid wager.
And that is what I mean by wagering being more important than handicapping. Spending your time splitting hairs between the #5 and the #8 is just plain dumb. Spending time understanding the wagering picture in a race is very smart. Understanding the wagering situation means that I don't have to look too closely at the #5/#8 situation AT ALL. If those two are close at all, take the #5!
It is SO MUCH about wagering, and not handicapping.
Take a look at yet another wagering statistic from the same track using the same 2/1 fav, If I take my SAME RANKINGS and instead make a three-dog box tri, what then?

3-dog box: 80 hits out of 1286 races (6.22%), average payoff is $89.66, and the ROI is a miserable -53.52%. (BTW, the 6.22% hits is very reasonable for a three-dog box.)

So,I take the EXACT same handicap and bet it three ways:

123/123/123 (3-dog box) (stupid, -53.52% ROI)
or
12/1234/1234 (meerly dumb, -1.07% ROI)
or
12/1234/5678 (sweet, +62.84% ROI)

The HANDICAP isn't important. The WAGERING means the world! Just LOOK at that spread. The BAD wager has a 53% LOSS and the GOOD wager has almost a 63% PROFIT! All based on the exact same handicap.

In all my years at the track, I've never seen ANYONE that can improve their HANDICAPPING from a 53% loss to a 63% profit. But you CAN improve that much if you study wagering.