Four Starting Pitchers At Risk of Walk Rate Increases

Yesterday, I discussed four starting pitchers due for an improved walk rate moving forward, according to my expected walk rate equation. Today, I’ll highlight another four pitchers, this time a group who is at risk of suffering from an increased walk rate over the rest of the season. These pitchers all sport xBB% marks well above their actual marks.

Collin McHugh | 4.7% BB% vs 7.4% xBB%

As one of last season’s out of nowhere breakout stars, it was difficult to project McHugh’s performance this year. And although his strikeout rate has tumbled below 20%, his overall skill set is solid and his SIERA has remained below 4.00. An inflated BABIP and HR/FB rate have both conspired against him to raise his ERA above 5.00.

His reduced walk rate has been one of the few positives, but he’s actually throwing a lower rate of strikes than he did last year. In fact, his current strike percentage is actually lower than the league average, yet his walk rate sits significantly lower than the average pitcher. So we should probably expect his walk rate to rise. That sounds like bad news to those considering buying low. But the good news is that his strikeout rate dip is primarily driven by a decline in foul strike rate. That’s the flakiest of the strike types and least consistent. His rate of swinging strikes has only dropped marginally, so it provides owners with some optimism that he could push his strikeout rate back above 20%. I’d buy low here.

Yovani Gallardo | 6.9% BB% vs 9.6% xBB%

Because I’m a super nerd, my xBB% file contains historical data. That means that when I dive into the names that make these lists, I could look at their past as well to see if they have consistently outperformed or underperformed their expected marks. Sure enough, Gallardo has posted walk rates below his expected walk rate for the past five seasons! But the gap between his BB% and xBB% right now would still be the largest of his career, so we have to assume something gives.

For the last four years, he has outperformed his xBB% by 2.1% on average. That’s significant. It suggests that he’s doing something that my equation isn’t capturing. Since I know that ball/strike sequencing is a big part of the missing puzzle piece, perhaps he’s good at stringing strikes together and spreading out his balls (haha) better than other pitchers. I would still bet on an increase in walk rate, but not as much as xBB% suggests. And when that rises, so too will his SIERA. That BABIP is going to jump and once it does, his ERA is going to head toward 4.00.

Jesse Hahn | 5.4% BB% vs 7.6% xBB%

Hahn has seemingly traded strikeouts for control as his strikeout rate has fallen precipitously, while his walk rate has almost been cut in half. But has he really become a control artist? His strike percentage is up just 0.9% from last year and it still sits below the league average. He’s also throwing a lower rate of first pitch strikes, so one wonders how he has managed to snip that walk rate so impressively.

An increase in fastball velocity hasn’t helped his strikeout rate like you would figure and his curve is just not getting anywhere near the whiffs it got last year. But we can’t completely ignore last season, even if it was in a relatively tiny sample, and his minor league strikeout rates gives us hope better is coming. He’ll need to increase that strikeout rate if that walk rate does jump, or he’ll be looking at an ERA above 4.00 the rest of the way absent good fortune.

Jake Arrieta | 4.9% BB% vs 7.1% xBB%

Arrieta enjoyed his long-awaited breakout last season and posted an ERA below 4.66 for the first time. So what has he done for an encore? Record nearly identical skills, but with even further improved control. All of his strike rates are nearly identical to last year, but his strike percentage has risen marginally. It’s seemingly not enough to support the further drop in walk rate he has posted so far.

That said, it doesn’t really matter. His SIERA sits at a wonderful 2.70 and he has suffered from both an inflated HR/FB rate and BABIP. So any jump in walk rate should be accompanied by better fortune on fly balls and balls in play. You never know when a young pitcher breaks out if it’s sustainable or if the league catches up and adjusts the following year. I think it’s obvious at this point that for Arrieta, it’s the former.