One of the fascinating things about re-reading Holmes is noting that, despite its strong congruity with the LBBs -- specifically the LBBs + Supplement I -- it's also full of idiosyncrasies. In some cases, like the oft-mentioned magic missile spell description, these idiosyncrasies are completely understandable. They're clarifications of ambiguities in the OD&D rules, albeit ones whose interpretation failed to find favor with the powers that be and thus was relegated to a footnote in the early history of the game.
Others, though, are just out of left field. A good example of this are the thief's saving throw numbers. According to Greyhawk, "with regard to saving throws treat Thieves as Magic-Users." However, Holmes treats thieves as if they were fighting men with regards to saving throws. Now, this decision is completely justifiable and, on a lot of levels, I rather like it, but why did he make this change? Indeed, was it even his change or was it something imposed on the rules by Gygax or someone else at TSR? The latter seems unlikely, given that AD&D doesn't follow this logic, but could it have been something that was being considered at the time Holmes Basic was being edited?
There are a lot of "Holmesisms" in the Blue Book. I'm slowly working my way through its 48 pages and cataloging them all and it's really fascinating to see. As I'm likely to say a lot in the coming weeks, the Holmes rulebook is an amazing historical document if you're interested in the development of Dungeons & Dragons.