I would like to know what the general consensus is on a MEARS vs PSA LOA on bats.

I recently came across this Ruth bat on Infinite Auctions and noticed that it only had a MEARS LOA, and the date range of the bat according to MEARS was form 1921 - 1931. I emailed John Taube about the bat, and he pointed out that the date range of the bat was 1923-1925.

I then looked through Malta's book on dating LS bats (A Complete Reference Guide Louisville Slugger Professional Player Bats), and saw exactly why John dated the bat to a 3 year span vs an 11 year span.

So, my question is, does MEARS not use Matla's book as a reference guide when dating their bats? If not, is it because there are questions about the book? Do they not want to use a competitors reference guide? Or, are they just lazy?

What do you guys think?