They were the first and last directors appointed after Leon Schlesinger sold the cartoon operation to Warner Brothers, which I think probably made for a tough situation: the studio was changing, becoming more beholden to the studio and its corporate needs, and there was no longer a question, as there had been under Schlesinger, of a director learning on the job. McKimson and Davis were in a big cartoon factory, expected to make cartoons for super-popular cartoon stars and come up with popular new continuing characters ASAP. And they were dealing with management that had already made it clear that it wouldn't have the same kind of tolerance for freakiness or quirkiness that Schlesinger did. Neither of them became truly great directors, in my opinion, but they didn't have the benefit, as Clampett, Jones and Freleng did, of being able to strike out a few times while working toward something more interesting. (Yes, Clampett hit some bad patches in his Warners career; most of his 1941 cartoons are pretty slow and stolid, but he was growing out of what he'd done in the late '30s, and we wouldn't have had his better, faster 1942-6 work without that slow patch in between.) By some accounts Davis used to say that his unit was shut down because he was less willing than McKimson to do what Eddie Selzer wanted; that sounds like a self-serving argument, but there's no doubt that playing the corporate game was a new challenge at the studio. Jones and Freleng could get by because they were directors who had the skills of producers, who were, in fact, de facto producers of their own cartoons; under Schlesinger's hands-off regime, they had to learn (as Clampett and Tashlin did too) to be semi-autonomous. McKimson and Davis did not have those skills -- if you read Lloyd Turner's interview with Mike Barrier, linked below, it's clear that Davis had weaknesses as a boss and decision-maker -- and they were more analogous to the directors who worked for Disney or some other studio: their cartoons were skifully made, reflected their personalities to some extent, but they were more like staff directors than full-fledged bosses, and that can be seen in the fact that the people who worked for them often didn't have a whole lot of respect for them.
The question always comes up of whether Warners made the right choice in shutting down Davis's unit when it downsized from four cartoon units to three . I've usually said that if one of them had to go, it should have been Davis, because I strongly prefer the cartoons McKimson was making in the same period. And while I still have that preference, it's obviously not as simple as that. McKimson started with a number of advantages over Davis that contributed to the success of his early cartoons, starting with the obvious one, that he got started a little earlier and therefore had seniority as a director. It seems like anyone who headed up the "fourth unit" was given short shrift at the studio, and it didn't matter if he was a veteran; when Frank Tashlin came back to the studio in the '40s, he said, he had "lost my seniority" and wound up with some of the same problems as Davis's unit. As the junior director, Davis was in the position of not being allowed to make Bugs Bunny cartoons for several years and getting most of the budget-cutting measures (like Cinecolor cartoons). Also, McKimson and Davis came in just as the studio was moving toward assigning story men exclusively to a particular unit, so McKimson got Warren Foster exclusively, while Davis went through several story men before getting Bill Scott and Lloyd Turner, who were good but inexperienced. According to Lloyd Turner's interview, Davis didn't seem to have enough confidence to judge whether their stories were good or not; whether or not McKimson had the same problems with judgment, it didn't matter much because Foster was one of the most respected story people at the studio, and as with Mike Maltese, there was a certain built-in confidence that his material was good.
My biggest problem with Davis's cartoons, and I've said this before in various ways, is that they don't feel quite like Warner Brothers cartoons to me. It's hard to put into words what makes a cartoon feel like it fits the WB "house style," but Davis's cartoons in terms of plotting, gags and animation often feel like they came from some other studio. Lantz, in particular; he had a lot of Lantz people on his staff, and the format of
And it's not like Davis is breaking with the WB house style to do something very new and experimental; it's just that they feel a little more like the products of other studios that weren't usually as good as Warners anyway. McKimson made a few cartoons like that, like Corn Plastered, where if you take away Blanc and Stalling and a few of Foster's gags, you'd swear it was a fairly good Columbia or Terry cartoon instead of the fairly bad Warner cartoon that it is. But Davis's cartoons, with their somewhat weightless animation (unlike Clampett, he didn't have a lot of "solid" animation, wild-but-grounded animation like Rod Scribner did, let alone McKimson-style animation; Davis had great animators, but none of them brought a lot of weight to the characters) , post-war suburban settings and interchangeable little-wiseguy characters like the squirrel in Porky Chops or the termite in The Pest That Came to Dinner, feel to me like they wandered in from some other studio and got outfitted with the trappings and production values of a Warners cartoon.
McKimson's cartoons of the same period just feel a little more Warners-y, just in the style of gags, the look of the cartoons -- even the suburban cartoons don't look quite as antiseptic as the same settings do in "Catch as Cats Can" or something like that -- the portrayal of the characters (Davis's Porky is too ineffectual even for Porky; McKimson makes him a little rougher and just a little more competent even when Daffy is beating up on him), the more solid look to the animation. And the far greater number of radio -- and later television -- references and parodies, giving his cartoons a more pop-culture savvy feel than Davis's usually had. Some of that is due to Warren Foster, but I don't think all of it is; I just think McKimson nailed the house style better than Davis did. Maybe he just had a better eye for imitating what the senior directors were doing; borrowing characters and catchphrases from radio was something he learned from Clampett, and throughout the '50s he would try to catch up to whatever Jones or Freleng had been doing a year earlier.
You could maybe argue that Davis lost the battle, in part, because he was trying new stuff (or at least new for Warner Brothers) while McKimson was content to master the house style and then never deviate much from that style. That might actually be a fair argument. But it's not surprising that when you have two "house directors," the more successful one is the guy who sticks closest to the house style. McKimson had weaknesses that would bite him in the ass as his tenure continued, most obviously his pedantic insistence that animators stick to his pose drawings, something that drove a lot of good animators out of his unit. Davis gave his animators maybe too much freedom sometimes, so this is one of those cases where a happy medium between the two approaches would have been best. But as almost anybody will attest who grew up watching these cartoons on Saturday morning, McKimson's cartoons feel very much like Warner Brothers cartoons; they fit the brand almost perfectly. I don't quite get that from Davis; I always feel like he would have done his best directing at some other studio. That's just me, though, and I wouldn't argue strenuously with anyone who feels Davis was better.
(I should note as an aside that while Chuck Jones is sometimes accused of similar pedantry, it's not true; Jones specifically said that Ken Harris ignored many, sometimes all of his drawings but that whatever Harris came up with would be the emotion that Jones had in mind; the directors' drawings were just a way of suggesting what the animator should try to convey.)