Defense big reason for Cubs’ success early in season

Starting pitching has received much of the credit for the Cubs’ fast start, and deservedly so. Entering their doubleheader Monday against the Cardinals, Cubs starters had a 3.17 ERA, second in the majors to the Indians’ 2.58.

But part of run prevention is defense. And despite a couple of missteps in losing three of four games to the Brewers, the Cubs have been stellar in the field, too.

Through their first 19 games, the Cubs stood fourth in the majors with a .731 defensive-efficiency percentage, meaning they had converted 73.1 percent of balls in play into outs.

The Cardinals led at .773 through eight games, followed by the Dodgers (.746 in 23) and Twins (.739 in 22). The major-league average is .700.

When the Cubs won the World Series in 2016, they led the majors with a .728 DefEff, 25 points better than the runner-up Blue Jays. They dropped to .699 in 2017 (the major-league average was .688), then were at .700 in 2018 (the major-league average was .691) before plummeting to .681 last season, seven points below the .688 major-league average.

The easy way to find defensive efficiency is to check the league defense pages at Baseball-Reference.com. For those who like a more hands-on approach, the formula is 1 - ((H + ROE - HR) / (PA - BB - SO - HBP - HR)). In addition to the common abbreviations, ROE is ‘‘reached on error.’’

DefEff treats hits and ROE in the same way. Both are balls in play that the defense didn’t turn into outs. If a runner reaches first on a grounder through the infield, it doesn’t matter if the fielder didn’t get to it and it’s labeled a hit or if it went off a fielder’s glove and is labeled an error. All that matters is whether the defense turned the batted ball into an out.

There are more advanced defensive measures than DefEff, including defensive runs saved. Advanced measures require human intervention to judge location relative to position and factor in how hard the ball is hit and other factors.

The object is to determine how many plays a fielder makes compared to an average fielder. DefEff can’t account for where or how hard a ball is hit, and sometimes teams that are strong in runs saved will fall short in DefEff. That’s the case with the White Sox, who rank fourth in the majors with 12 runs saved but 23rd in DefEff at .691.

The Cubs fare well with 14 runs saved, second to the Dodgers’ 21. Because comparisons are to average, an average fielding team would have zero runs saved. The Cubs were well below that line last season with minus-28 runs saved.

Catcher Willson Contreras is the team leader with three runs saved, followed by Albert Almora Jr., Javy Baez, Yu Darvish and Anthony Rizzo with two each.

Defensive efficiency isn’t as advanced as runs saved, but it’s much more advanced than fielding percentage. And by either DefEff or runs saved, defense has been a plus in the Cubs’ early success.