Just how good is Ichiro Suzuki's arm?

Let's go back in time to April 11, 2001. Ichiro Suzuki had signed with the Mariners in the offseason, who had taken something of a risk in bringing him in. As the first Japanese hitter to come to the majors, he had a lot riding on his diminutive shoulders. And on that day, when given an opportunity to prove himself...well, this happened:

When I think of iconic plays that have occurred in my lifetime, this one usually shoots to the front of my mind, along with David Freese's triple and Derek Jeter's flip to home. Sure, Ichiro's throw didn't have any postseason implications, but something this legendary takes on a life of its own. This proved to the entire country that Ichiro was here to stay — and to be feared.

In reflecting on Ichiro's major-league career, many people will discuss his performance at the plate. Others will talk about the incredible base-stealing ability he possessed, or the fielding range that set him apart. I want to look to this more minute facet of Ichiro's game, because there's an interesting discrepancy between two evaluations of his arm.

UZR and DRS, as you likely know by now, are two of the most common defensive metrics. Usually, they agree; sometimes, they don't. Most of the disputes stem from range: For instance, Alfonso Soriano has 74.4 UZR in the outfield, on the back of 65.9 RngR, whereas his subpar -13 rPM sinks his DRS to -1. While the systems may have difficulties with catching, they tend to see eye-to-eye when it comes to throwing — but not always.

Since DRS began in 2003, 192 outfielders have accumulated at least 3,000 innings. This shows their arm ratings by both metrics:

See the lonely dot that sits far to the right of the y-axis and slightly below the x-axis? That's our man. Over 19,310 lifetime innings in the outfield, Ichiro has saved his clubs 30.4 runs with his arm, according to UZR. In DRS's opinion, by contrast, he's cost his teams 4 runs in this area. Which estimate is the accurate one?

Let's begin with the most basic measure of arm strength: assists. If an outfielder can make a habit of cutting down runners, he'll obviously help his team. But Ichiro hasn't done that all too often. He's racked up 116 assists, an average of 6.1 per 1,000 innings; since 2001, the average outfielder has thrown out 6.5 baserunners per 1,000. The epic Long play seems like an aberration, one that doesn't reflect Ichiro's more mediocre true talent.

This analysis, however, doesn't do Ichiro justice. Both UZR and DRS base their arm ratings on similar areas. Here's Mitchel Lichtman on the former:

[...O]utfield arm run values are also computed separately from "regular" UZR. They are based on the speed and location of batted balls to the outfield and how often base runners advance extra bases (advances), don’t advance the extra base (holds), or get thrown out trying to advance (kills)

And here's the Fielding Bible on the latter:

We account for the strength and accuracy of an outfielder’s arm by comparing the rates at which runners advance in potential extra-base situations. In extra base situations, the runner could either 1) advance safely, 2) get thrown out attempting to advance, or 3) hold at the previous base and not challenge the outfielder.

While kills count for something, the most important skill is preventing runners from moving ahead. And this is where Ichiro has earned his keep.

Baseball-Reference has a metric called Hold rate. It looks at a number of potential advancement scenarios (which we'll delve into momentarily) and tracks how well an outfielder performs in each of them. For his career as a right fielder, Ichiro has an overall Hold rate of 50.9 percent, significantly above the major-league average of 46.7 percent. As a center fielder, he's posted a Hold rate of 48.8 percent, compared to the MLB-wide mark of 45.0 percent. And his Hold rate of 63.8 percent over limited time in left field matches the average figure of 63.9 percent. Ichiro hasn't made the flashy plays, but he's still made himself valuable.

Plus, this success comes from each variety of hold. This metric has five components:

• Runners advancing to third from first on a single;
• Runners scoring from second on a single;
• Runners scoring from first on a double;
• Runners advancing to third from second on a fly ball; and
• Runners scoring from third on a fly ball.

For these, we'll zero in on right field, where Ichiro has compiled 16,074.0 of his innings. In all five regards, his production stands apart:

After base hits, Ichiro has done a solid job of keeping runners in place. After fly balls, he's done a spectacular job. His stats in center and left show the same uniform trend: Across the board, Ichiro has intimidated runners.

Perhaps the lack of kills means Ichiro doesn't have a great an arm as we think. If that's the case, then his reputation likely accounts for his talent here. Maybe plays like the one Ichiro made on Long have continued to linger in the minds of opponents, even though they don't represent his true talent. If that's the case, though, then Ichiro has still earned this — he was the one who eliminated Long, after all. A reputation, deserved or not, still helps a team, which means its owner has value.

So why do the advanced metrics disagree? Lichtman mentions that UZR has a park factor built in, to adjust for the fact that different dimensions can allow for more or less advancement. Although I'm far from an expert on DRS, it doesn't seem to have this feature. Since Safeco Field has such large dimensions, hitters have more leeway to move ahead when they so choose; perhaps UZR corrects for this, and DRS does not. Whatever the cause, Ichiro's peripherals certainly appear to endorse the former.

If when Ichiro finally decides to call it quits, we'll look back on his career and think of the big plays. This man consistently hit for a high average, stole a ton of bases, made incredible catches look routine, and gunned down Long and others with ease. But the little things that he did made him a true great. Like his sprint down the first-base line, Ichiro's ability to block advancement separated him from his peers.

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Ryan Romano is a contributing editor for Beyond the Box Score. He also writes about the Orioles on Camden Depot (and on Camden Chat that one time), and about the Brewers on BP Milwaukee.