James Click, a former Baseball Prospectus writer and currently the Rays director of baseball research and development, analyzed the question in the 2006 book "Baseball Between the Numbers" and came to a definite conclusion.
"Protection is overrated," Click wrote. "There's no evidence that having a superior batter behind another batter provides the initial batter with better pitches to hit; if it does, those batters see no improvement as a result."
If an opposing manager or pitcher does take protection into account and walks a batter to get to the next one, Click wrote, it's almost always the wrong choice.
Tampa Bay first baseman Carlos Pena would largely agree with Click's thoughts, calling the idea of lineup protection a "pretty good theory." Joe Maddon, Pena's manager and arguably the most analytic skippers in the Majors, would mostly disagree.
If anything, the fact that it's a question worth asking is perhaps the strongest evidence that it exists.
"There's still the human element involved regardless of all the data that's there. It's about buying in with whomever's using it," Maddon said. "Some people believe it more than others; some people don't believe it hardly at all.
"At the end of the day, when you're the pitcher out there, and so-and-so is hitting with so-and-so on deck, regardless of what you know numerically, a lot of times you're still going to go with what's in your heart or in your gut."
That could be what makes the Kemp-Ethier pairing, to use one example, so important. Pitchers don't want to pitch to Kemp, knowing that if they do, there's always a realistic risk of turning around to see their offerings land somewhere in the bleachers. But they can't simply walk him on sight, because Ethier is more than capable of driving in Kemp and setting up a big inning -- often a worse outcome than Kemp hitting a homer or recording an extra-base hit.
Realistically, with that in mind, the pitcher would be better served to take his chances with Kemp then do the same with Ethier with a man on base. But if the pitcher and catcher are worried enough about Ethier in the on-deck circle while Kemp is in the batter's box, Maddon would argue that all the run-expectancy charts and data don't mean anything. Kemp will see better pitches because Ethier is in the pitcher's head.
"Absolutely -- or even the manager's head, or even the pitching coach's head or even whomever's head," Maddon said. "Everyone talks about the data and how wonderful it is, and I'm truly a believer, but there's also the buy-in component also. Unless you have total buy-in from everybody involved, it doesn't necessarily have the same impact."
But the amount of data now available makes lineup protection seemingly less important than how it's been perceived.
Each at-bat has become more of a nuanced chess match, with pitchers receiving highly detailed scouting reports about how to attack each hitter in which count with which pitch and so on. Pitchers, catchers and managers are more aware than ever of hitters' weaknesses, meaning they can almost pitch around a batter by simply pitching to him the "right" way -- using their strengths to exploit his weaknesses.
"In the long run, it may make a difference, but the game right now is so advanced that I'd say it's not as big of a deal as it used to be," Pena said. "With scouting today, pitchers are still able to go to work on a hitter unless they're really behind [in the count]."
It used to be more of an issue, Pena admitted, and it probably still is at levels of the game where the scouting reports and data aren't so meticulously prepared. That's true in several ways regarding how pitchers attack batters, as Pena pointed to the idea that a player is going to see a lot more fastballs when leading off an inning.
"That's not true. If I'm batting leadoff, they'll just say, 'I'm not going to pitch to his strength,'" Pena said. "I don't care whether he's ninth, fourth or leadoff. I'm still going to try to get him out. Pitchers are no longer saying, 'Oh, that's the leadoff hitter, maybe I should get ahead, here's a fastball.' If I'm hitting leadoff, they're not going to do that."
In other words, the days of essentially pitching around elite hitters might be a thing of the past. Perhaps they should be, if the information at clubs' fingertips is properly utilized and the strategy gleaned from that data is properly executed.
"Things have changed. Pitchers are more prepared with the scouting they're getting," Pena said. "The reports are so extensive that it could really go a long way."
At the end of his analysis, Click explained that the "conventional wisdom has become self-fulfilling prophecy -- batting order is important because everybody thinks it's important."
In other words, as Maddon said, lineup protection will exist so long as the people on the mound, behind the plate and in the dugout believe it's important.