A tale of two halves: the Mariners’ offense

Those famous words perfectly capture the contrast we’ve seen from the Mariners’ offense this year. We thought adding Nelson Cruz to a mediocre offense would help it rise out of the morass of the American League. It took a while—through no fault of Cruz's—but that offense has finally flourished over the last three months. Unfortunately for the Mariners, it was three months too late. With this season all but over, which version of the Mariners offense could we see next year?

If you’ve been following along with my series previews, you might have noticed that the Mariners’ offense has risen above league average this month (per team wRC+). It’s been a long a winding road to get there but a strong second half has propelled the offense into the upper echelons of the American League. Taken straight from each series preview, here’s a graph showing the Mariners’ team wRC+ starting from late April to now:

That steep decline beginning in early June coincides with a stretch of games where the Mariners faced the Rays, the Indians, and the Yankees 17 times in 18 days. In a tour of American League Cy Young candidates, they faced Chris Archer and Corey Kluber twice each, and Michael Pineda and Masahiro Tanaka once each in those 17 games. The Mariners went 7-10 over that stretch and scored just 47 runs (2.76 runs per game). That was the low point.

After the All-Star break, something clicked for the Mariners. They started scoring runs in droves and they haven’t let up. Observe:

Mariners	BA	OBP	SLG	BABIP	BB%	K%	wOBA
1st Half	0.236	0.296	0.382	0.277	7.4%	21.6%	0.295
2nd Half	0.267	0.329	0.452	0.317	8.3%	22.3%	0.337
Lg Avg	0.256	0.318	0.413	0.297	7.6%	19.8%	0.317

Across the board, the Mariners were below league average in all of these key offensive stats in the first half. That’s almost completely flipped in the second half, with just the team’s strikeout rate moving the wrong way. We’re looking at two almost completely different teams here. Their improvement isn’t spurred by just more home runs either (though the team’s ISO is 40 points higher in the second half). The Mariners are walking more often and their balls in play are finding green more often.

What about on a more granular level? Let’s take a look at two metrics on a month-to-month basis:

The teal line graph shows team wOBA and the vertical bars show runs scored per game with the league average for each metric in grey. The Mariners were well below average during the first three months of the season, bottoming out in June with the worst offense in the Majors. Since then, the Mariners’ team wOBA has been in the top third of the league and they’ve been scoring runs at an above average rate. Before the season started, Lloyd McClendon said that if the team was able to score at least four runs per game, they would be fine. Well, that wasn’t true in the first half but it’s been certainly true in the second, and their record reflects that.

Looking Ahead

Now that we’ve examined the Jekyll and Hyde performance of the Mariners’ offense this year, what does 2016 hold for the team? We can’t just extrapolate their second half performance directly to next year. We can take a look at who has been driving this offensive resurgence and try and determine a rough projection for next year.

Here are the Mariners’ batters’ wOBA splits sorted by the greatest gains in the second half:

Jesus Sucre leads the pack because his first half wOBA was so low, it included an extra zero. The other big gainers are promising as well. Robinson Cano has recovered from his early season issues and has added almost 100 points to his wOBA. Mark Trumbo struggled mightily after being traded to the Mariners but has looked like a completely different player recently. Even Nelson Cruz found a way to improve on his already impressive first half. Remarkably, Seth Smith is the only Mariner who has seen his wOBA fall significantly in the second half.

Again, we can’t just extrapolate second half performance directly to next year. Despite how it may seem, Nelson Cruz probably won’t run a wOBA over .400 next year. Luckily for us, FanGraphs provides tools that we can use to make an educated guess about next year’s team. For the two most popular projection systems, ZiPS and Steamer, FanGraphs provides in-season projections. These projections update the preseason projection with the player’s performance during the year to spit out an estimation for what the player might do for the remainder of the season. The counting stats from these projections are going to be useless but the rate stats should give us a decent picture of how these projection systems expect players to perform in the future now that almost an entire season has been played.

Here are the Mariner batters who are under team control in 2016, their 2015 wOBA, and their projected wOBA via ZiPS and Steamer:

The difference column is just the difference between a simple average of the two projections and the player’s performance this year. The projection systems think that Mike Zunino can’t be any worse than he was this year. Nelson Cruz probably won’t have another career year next year but he’ll still be an offensive powerhouse. The projection systems don’t know what to do with Ketel Marte but there aren’t many 21-year-old shortstops doing what he’s been able to do this year. They still love Logan Morrison and Jesus Montero, but for the most part, what we’ve seen from the Mariners this year will be true next year.

That reality might not inspire much confidence for some of you but consider the team’s overall offensive output in the waning weeks of the year. The Mariners have had a top-5 offense for three months now and that’s pushed their season stats just above league average. The true talent of this team’s offense probably lies somewhere in between the peaks and valleys of this year. It’s unfortunate that the team has struggled through some wide swings in performance this year, but overall, the team has scored runs almost exactly how we expected them to.

If we can estimate a steady overall offensive performance from this year to next—without adding any players—we may be looking at one of the better offenses in the league. The biggest question facing the next GM will be to determine if the current window of opportunity warrants a win-now approach or a full-scale rebuild. Based on these back-of-the-napkin projections, he or she shouldn’t have to worry about the offense too much.