Do Rookie Regulars Wear Down in the Second Half?

The Cubs’ offense began to break out of its weeks-long slump in its first two series out of the All-Star break. Their runs scored by game, since the break, read: 2, 4, 4, 4, 5, 1, 6. That’s hardly an explosion, but for a team who scored 51 runs in their final 20 games before the break, it qualifies as encouraging progress. It’s also a relief, because there were some who thought this offense might never rediscover its early-season punch. Specifically, there’s been considerable concern about Kris Bryant, Addison Russell and Jorge Soler, none of whom have played especially well over the last two months.

Cubs Rookies, Since June 1st

Sure, Soler’s struggles come in a small sample, as he missed virtually all of June with a sprained ankle. And sure, Russell’s strong start to the second half has been encouraging. The latter is baked into the ugly numbers above, though, and because I started on June 1st (just to take a non-selective snapshot), this table doesn’t really reflect the major problems Bryant has had since mid-June.

It’s part of the narrative that has trailed this team all season: young players need time to adjust. It takes 1,000 at-bats before most players find their groove in the majors. The Cubs (sing it with me) are really still a year away. This is the prevailing wisdom, and while there’s truth to it, it’s a frustrating oversimplification of the case. For one thing, the Cubs are contenders, so it’s not acceptable to simply shrug and toss a cliche at the issue. Underperforming is a problem right now, because it threatens the viability of what could be (even should be, at this point) a playoff season.

For another thing, though, these young Cubs hitters are not supposed to be just any young hitters. Bryant and Soler, in particular, drew extremely rosy preseason statistical projections, in addition to all of the scouting love. These were players who were supposed to succeed more immediately than their peers, and crucially, they did so, at least early on. (Soler, admittedly, has never truly found his groove. Bryant and Russell, though, have each had significant stretches during which they’ve been markedly above-average at the plate.)

Yes, they’ve had success, but they’ve also had that recent failure, and that has fed not only the broad narrative of young players’ rough adjustment periods, but a more specific one, often voiced by those who don’t believe in the Cubs’ staying power in the playoff picture: maybe rookies, especially those who are especially young or are playing their first 160-game schedules, struggle to keep up their production in the second half.

That’s the theory I wanted to test, not only because Bryant, Russell, and Soler have begun to fulfill that narrative in recent weeks, but because the Cubs probably need more than survival from those guys down the stretch. Without an outburst from at least two of those bats, Chicago probably doesn’t have the offense to fuel more than a modest Wild Card run.

To examine the possibility spectrum for this trio (but mostly, for Bryant and Russell), I searched Baseball-Reference’s Play Index for all players since 1988 who:

• had rookie status;
• were 25 years old or younger; and
• accumulated at least 600 plate appearances in that rookie season.

There have been 48 such players over that quarter-century. For each, I sought out their first- and second-half split statistics, looking primarily at whether they did better in one or the other. I didn’t break it down by month, because variance would wash out any meaning in the data, and I didn’t aggregate the stats, because that would have done more harm than good. Here, though, are all 48 of the platers in the sample, sorted according to whether they were better in the first half, better in the second, or neither.

Rookies Ages 25 and Younger, 1988-2014, First and Second Half Splits

This is a really simple, unscientific way of trying to test the notion that rookie regulars wear down. As far as it goes, though, it rebuffs that idea. Rookies who really fell apart late in the season, of course, might be less likely to reach 600 PA, simply because their managers might remove them from the lineup. Then again, a very strong first half can keep a player in the lineup even as his performance nosedives, so the biases pull both ways.

In general, the finding here is: Kris Bryant and Addison Russell aren’t likely to fall apart. They’re certainly no more likely to remain in slumps than any other player in a similar funk (Anthony Rizzo, Dexter Fowler, or Starlin Castro, for instance) would be. Rookies don’t burn out or collapse with unusual frequency, which should be a relief for the Cubs and their fans. This team will go only as far as those young hitters take it.

Lead photo courtesy of Caylor Arnold-USA TODAY Sports