Cubs Have Baseball’s Best Rotation, But Do They Need to Improve It Anyway?

There’s been plenty of talk about the Cubs going after another arm, kind of a way to October-proof the pitching staff or some such. I suppose that’s a solid plan if you fall into the “if it ain’t broke, fix it anyway” camp, particularly when you take into account the history of the men who make up the back end of the rotation.

Jason Hammel has been brilliant thus far in 2016 and recently dominated the Cardinals in St. Louis to move to 6-1 with a 2.17 ERA. As great as he’s looked though, there’s a pervasive sense in the backs of more than a few minds that it’s all temporary. Whether you chalk it up to fatigue, trade, or injury, Hammel has not exactly been a great second-half pitcher over the course of his career.

Heading into Tuesday’s start, Hammel’s first-half ERA and FIP splits both stood at 3.96, while those respective numbers numbers were 5.15 and 4.49 post-break. There are plenty more alarming stats to reference, but to do so would only be to further assume that Hammel will fall back into the same pattern again. While that’s certainly possible, it’s just as likely that his new fitness regimen and the Cubs’ ability to provide a bit more grace for him will prevent such slippage.

Though he doesn’t have nearly the track record, Kyle Hendricks experienced a similar drop-off in the second half last season. In his case, fatigue may have been to blame. Hendricks appeared to have hit a wall as the summer wound down and really struggled with his control for the most part. He was both striking out and walking more batters, a sign that he was unable to locate the zone quite as well. But while his ERA jumped from 3.55 to 4.44, his FIP and xFIP were both down after the All-Star break.

Again, these are all numbers from the past. You can stand on them as solid predictive models if you want to, just be sure to let me know if you’re going to climb up there so I can get out of the way before you take a tumble. I’m not saying Hammel, Hendricks, and the rest of the rotation will maintain their current pace over the course of the next four-plus months, just that to immediately assume they won’t is doing them a disservice.

Consider that Cubs starters are carrying a collective ERA of 2.51, more than half a run less than the second-best Washington Nationals (3.04). The Cubs rotation also boasts the league’s lowest FIP (3.05) and most total WAR (6.6). Much of that comes from allowing fewer home runs (19) than any other other staff in baseball, more is from avoiding free baserunners and hard contact. A solid strategy to be sure, now the question becomes whether they can keep it up.

The rotation has limited opposing hitters to a measly .253 BABIP, 18 points lower than any other team has allowed. Their home runs per fly ball rate of 8.4% is also the lowest in the game. This tells us that the Cubs might be getting out over their skis a just a tad at this point, which is to say that perhaps they’re getting a little lucky. Then you have to acknowledge that the excellent collective performance is having another, perhaps unintended, consequence: Cubs starters are going deeper into games than those for nearly any other team.

After all the talk this winter about saving innings, Joe Maddon has done little to back up his words. Cubs starters are on pace to log 1,030 innings this season, just over 83 more than last season. To be fair, some of that comes from the addition of John Lackey to the middle of the rotation. Jon Lester is trending toward a lower total, but that’s only due to his recent abbreviated outing in San Francisco. Jake Arrieta’s on pace to throw a couple innings more than last season’s 229 — a quantum leap over his previous career high — as well.

In the case of the back-end starters, however, pitching more innings would be a good thing. Hammel failed to go deeper than 5 innings in 11 of his last 15 starts last season and failed to go past the 4th inning on six occasions in that stretch. Likewise, Hendricks failed to complete 6 innings in eight of his final 15 starts. Not awful by any means, just indicative of inconsistent performance. That certainly hasn’t been the case to this point of the 2016 season.

Unless either Hendricks or Hammel really does drop off, you’re going to be hard-pressed to find an available pitcher who’s going to offer better value than what those two already do. The Cubs probably aren’t going to move either to the pen, so adding an arm would be more about expanding to a six-man rotation in order to keep guys fresh for the postseason. It’s not a strategy I’m particularly fond of, but it would enable them to limit total appearances rather than artificially cutting individual outings short.

If that’s all they’re going to do, they’re better off going with the occasional bullpen start or calling on Ryan Williams or Pierce Johnson or [insert prospect here] every sixth day down the stretch.

While it’s not quite the click-bait silliness of the Cubs wanting to trade for Ryan Braun, I’m not sold on the idea of wanting or needing to go after a big-time starting pitcher. It’s not so much that they wouldn’t want to add another elite arm to the mix, because any team would love to do that. It’s that the cost to acquire the type of starter the Cubs would want is going to be prohibitive. With the market value of starting pitching what it is right now (thanks, Dave Stewart), it’d be silly to mortgage the future for anything shy of a cost-controlled sure thing.

That’s all speculation though, as is looking ahead to predict how the starters continue to hold up over the next few months. I don’t need a crystal ball, however, to tell you that the Cubs’ starting rotation has been every bit as good as the prolific offense to this point in the season. How Maddon and the front office choose to go about maintaining that is going to be an interesting trend to follow as the summer wears on and the innings pile up.

So do they need to think about improving what has been baseball’s best rotation so far? For my money, the answer is a solid no. Then again, it’s not my money the Cubs are using.