The rise of sabermetrics in baseball in the late 2000s led to the creation of something of a collective framework for the "smart" way to think about baseball. There were and are rules of thumb for what's smart and dumb with respect to in game strategy and player acquisition. Reasonable people could disagree about players and strategies, but there was a consensus around some base principles that no one would really dare breach.
Most of these rules were developed and accepted in what has to now be thought of as a different baseball era. From 1993 to 2009, MLB teams on average never scored fewer than 4.59 runs per game. The next 5 years were all well under that threshold, bottoming out with 4.07 per game in 2014. The average hasn't fallen below 4 since 1976. This is still the same game, but some of the sabermetric rules of thumb have changed a bit.
Part of the reason for the dropoff can probably be attributed to the expanding strike zone. This great article from Jon Roegele at the Hardball Times last October has some nice visualizations of what that has looked like. The strike zone has been trimmed vertically in the past 5 years or so but has expanded about 3 inches downward on the bottom. Reasons for this might vary but a compelling idea is that pitchers are adapting and throwing more (and better) sinkers and cutters. Another idea is that more attention is being paid to the skill of framing pitches by catchers, and as a result pitches in the bottom part of the zone look better and are being called strikes more often.
This is a transitional phase for MLB, so it is tough to predict what happens next. Maybe MLB instructs umpires to be more stringent on low-zone pitches with movement and the run environment bounces back, or maybe they make other rule changes. But for now there might be some opportunity to take advantage, and the Brewers may be well-positioned to do so. Below are some poorly organized thoughts about how they might be going about it, whether they are aware of it or not.
Speed and baserunning
One good example of a sabermetric "truth" like I mentioned above is the base-stealing breakeven point. The new conventional wisdom was that base-stealing can be worth it when the success rate is high enough, but that in general, attempting to steal too much can cost a team runs. In a lower run environment, that breakeven point can fall just a bit, and stealing bases in bulk could prove to be a greater asset. The Brewers were 6th in 2014 and 1st in both 2013 and 2012 in the NL in stolen bases.
In the 2000s a mid-rotation (average) starting pitcher was quite a valuable asset for a baseball team. In general, a team should want to know at which position it can most easily find a replacement-level player. The basic theory behind WAR and most value metrics is that over a full season, an average player is worth about 2 wins more to his team than a "replacement level" player, the kind you can pick up on a minor league deal whenever you need one (think of an Elian Herrera-type hitter or a Mike Burns-type pitcher). In the past this theory has been matched pretty well by empirically looking at players of this caliber, both hitters and pitchers.
What could break down the system and create a spot for a team to pounce, however, would be if the average player at a certain position were to become closer to a replacement-level player for some reason. As a thought experiment, let's say that the position of shortstop were to become extremely difficult, and that only a few players could play it well, and that everyone else was more or less equally bad with a narrow distribution. A smart team might put resources toward other positions and just punt at shortstop, rather than paying for the relatively small improvement within the second tier.
I have a theory that something like this might be happening overall with respect to pitching versus hitting. These assumptions were made in an era of bigger offense, and if pitching is now a little bit "easier", a team might be able to get by with less pitching depth, as it might not be as difficult to find effective 6th, 7th, and 8th starters as it once was (that is, the difference between an average pitcher and a replacement-level pitcher may be smaller than it was then). At the same time it might be getting harder to find capable replacement-level players at positions like 1st base (something the Brewers can certainly attest to). If this were to be true, a team might focus less on pitching depth (**punt**) and focus more on finding average players to fill in gaps on offense because the reward for finding them might be greater.
An interesting field of sabermetric research in the past few years has delved into pitch receiving and framing. I mentioned it earlier as a potential explanation for the expanding strike zone, and as it turns out Jonathan Lucroy is thought to be one of the best in all of baseball at it (and Martin Maldonado tends to rate well, too). The best framers can get a few extra strikes per game for their pitchers. And for a team looking to shift gears in this new era, having catchers this conscious of good receiving helps alleviate concerns about the bottom end of a pitching staff.
I don't think the Brewers are all the way in on the sort of vague team-building blueprint I outlined here, but if you look closely enough, some of the signs exist. This offseason, their only two significant moves sacrificed starting pitching depth, often one of Doug Melvin's top priorities, to gain depth elsewhere. If things break right, they're a good offensive team in a this new pitcher's era, and they've put together a solid enough defense that it might help to mitigate some of the concern that limited depth in their rotation could derail the season. It will remain to be seen in practice if any of my theories laid out here are even correct in the data. But it sure is an intriguing concept.