The Kansas City Royals pitching staff, in a very small sample size, has pitched very well. There is evidence to suggest that the overall improvement can stick, but the amount of home runs they have surrendered is an area of concern.
As a group, the Royals pitchers rank fifth in baseball in ERA at 3.30. So far, that is a huge improvement over last season, when as a group Kansas City pitchers finished 22nd in ERA.
The pitching staff is currently backing up the low ERA number with strong strikeout and walk numbers. It's still too early in the season to accurately gauge how much these numbers will stick, but the early returns are promising. Kansas City pitchers are currently third in the league in strikeout percentage and own the sixth lowest walk percentage. This suggests that the pitching staff has earned their shiny ERA numbers with quality pitching, and are not over-reliant on forces outside their control.
The team's home run numbers, however, tell a different and more complicated story. Kansas City pitchers have allowed the sixth most home runs per nine innings in the league at 1.32 HR/9. Moving forward, Royals pitchers are unlikely to post such a high home run rate, but the home runs they do allow will likely hurt the team more.
I feel confident claiming that Royals pitchers will not continue to allow so many home runs because their current home run rate is quite high and would be difficult to sustain over a full season. The Toronto Blue Jays had the highest HR/9 allowed last season at 1.27. Unsurprisingly, the Blue Jays had the fifth worst ERA last season; despite what you may have heard, home runs can hurt you.
So I think it's unlikely that Kansas City pitchers end the season surrendering more home runs per nine innings than the worst team finished with last season. That doesn't mean that home runs couldn't be a serious issue for this pitching staff, especially as it starts to warm. Since 2010, James Shields, Ervin Santana and Jeremy Guthrie have all had at least one season with HR/9 of at least 1.5. HR/9 and HR/FB% are statistics that have high variance, so that does not guarantee that they will surrender too many round-trippers this season, but it is worth noting that the team's top three pitchers have struggled with the issue in the past.
Shields and Santana had issues with the longball despite pitching half of their games in parks that are harder to hit home runs in than Kauffman Stadium. Guthrie should receive some aid pitching in a more homer-neutral park than Camden Yards and Coors Field, but the Rogers Centre plays as homer-neutral as Kauffman. Pitching in Kauffman will not make as big off an impact in suppressing home runs as some believe.
Despite the picture I have painted, there is no reason to panic yet about the team's penchant for surrendering home runs. We don't have nearly enough data to confidently claim the team will continue to surrender home runs at a high rate for the entire season. The home runs the team does surrender, however, are going to hurt more moving forward.
About 58% of home runs are hit with no runners on base. While giving up solo home runs isn't ideal, it's certainly a lot less back-breaking than surrendering a three-run homer. Opponents are currently hitting 83% percent of their homer runs against the with no men on base, a number that screams regression towards the mean.
Some might want to argue that Kansas City has veteran pitchers who are more aggressive with the bases empty, so the pitching staff will naturally allow more solo shots. Even if this belief is true, it cannot account for the current 25% difference. There is simply not enough evidence that pitchers have a large amount of control over how many home runs they allow; a few pitchers have shown to have some home run prevention ability, but that evidence is not strong enough to suggest that home run prevention is an easily identifiable skillset.
The inverse of this argument is that pitchers who surrendered a ton of home runs in the past, like the Royals top three starters, may not actually be more homer-prone than the average pitcher. This is a valid point, which is why nobody needs to panic yet about the amount of home runs the team is surrendering.
The evidence should put to rest any notion that this particular group of pitchers will continue to allow solo home runs instead of multi-run homers. It's hard enough identifying pitchers who can control how many home runs they allow, so finding pitchers who control when they allow the home runs is even more difficult.
So after this discussion on Royals pitchers and the amount of homers they are surrendering I can confidently tell you this: we simply don't know enough to make many firm conclusions. The home runs they do allow will hurt more, but the pitching staff may not surrender enough home runs for it to drastically hurt the team's run prevention abilities.
There is simply no way you can confidently claim at this point of the season whether home runs will continue to bother Kansas City pitchers this season. I mean, you can stake out an opinion and say it with confidence, but the available evidence will not support your well-argued opinion in either direction.
Looking at the team's quirky home run numbers so far are a good reminder at how little baseball has been played so far this season. Nobody wants to wait before jumping to conclusions, but it's going to take more time before anyone has a good idea how much the pitching staff has improved. Me screaming about how bad the home run numbers are and will be for the rest of the season would be as disingenuous as someone else screaming about how awesome the team's ERA is and how awesome it will be for the next 148 games.
Instead, we should simply note that the team has had good luck with the timing of their home runs, but is currently surrendering too many. The pitching staff's home run rate is a red flag that has been raised early, but we still need more time to see how big of an issue it will be moving forward.