Author Archive

Properly Diving Into Expected Stats

“This player is having a good year, but his xwOBA is slightly lower than his wOBA, therefore he’s going to get worse.”

This is a common concept you’ll hear within the baseball analysis community. With the data made available to us, it’s easy to come to conclusions like this. However, it’s not always about the data made available to us, but the analysis that comes from it.

To better grasp how this “problem” of data analysis came to fruition, let us go back in time.

Starting in 2015, the public was provided with Statcast metrics for MLB players via Baseball Savant. Among those stats were exit velocity, launch angle, hard-hit rate, pitch velocity, sprint speed, and, to be honest, practically anything that can be measured! It’s a fabulous website that provides very useful information we should be exceptionally grateful for.

The most popular metrics on the website, however, are their expected stats: expected batting average (xBA), expected weighted on-base average (xwOBA), expected on-base percentage (xOBP), expected slugging percentage (xSLG), and expected isolated power (xISO). Essentially, these statistics are what you’d expect based on the name; they indicate what a player’s “true talent level is” based on the quality of their contact, frequency of contact, and, depending on the batted ball, sprint speed.

This would appear to be a gold mine on the surface. With the ability to know what numbers a player deserves to have, we should be able to separate their talent level from outside circumstances, and thus better predict future performance. Yet that actually isn’t the case. Read the rest of this entry »

Rethinking How We Look at Team Defense

They say that a run prevented is as important as a run scored, and this checks out. In fact, based on the coefficient of determination (r^2) for the two variables, a run prevented has actually been more correlated with team success than a run scored. This has indeed been labeled as the “run prevention era,” and just by that measure, this would appear to be the case.

As we’ve discovered in the past, offense and pitching wins championships, especially compared to defense. However, that certainly does not mean that defense does not matter. Rather, it is a small advantage that teams can leverage to continue to win between the margins. Small-market organizations such as Cleveland, the Rays, and the D-backs have all benefitted from strong defense in the past, while the Mets have been a clear example of what poor defense can do to you.

How can teams gain an edge defensively, and how much does it matter? What are the most important defensive positions, and how does it vary from the defensive spectrum? Should teams tailor their defense specifically to their pitching? Let us change the way we look at team defense by crunching through the numbers! Read the rest of this entry »

Stars or Depth? What Is the Best Way To Build an MLB Roster?

Building an MLB roster is anything but simple, to say the least.

It would be very convenient if it was as easy as playing MLB: The Show, but as we are well aware of, there are many complexities to roster construction. Not only do organizations need to have high-end talent, but they also need to have 26 quality big-leaguers as well other players in the pipeline when adversity hits.

In a perfect world, teams would be able to have tons of star talent as well as intriguing depth. However, we do not live in a perfect world, and for that reason, teams need to adopt a specific strategy when it comes to building the best roster possible in the most efficient way imaginable.

Teams have generally two courses: will they prioritize star talent, or will they look to have as deep a team as possible? The first option is typically known as the “stars and scrubs” approach, and it is one that you see often see in basketball. Meanwhile, the latter approach is one that you’ll see with sports with deeper rosters, primarily football. Overall, both methods are used frequently by teams, but it is unclear which one is the more efficient when it comes to roster building.

What good is there to posing a problem if we aren’t going to find the answer for it? We need to dig deep into these two approaches! Should teams prioritize star talent even if it means their depth is lacking? Or is quantity more valuable than quality? Let us try to discover the answer to this critical question! Read the rest of this entry »