Here's how you know Arenado is back

Here's a leaderboard that, if you're the Cardinals, you like to see right now.

Most pulled extra-base hits, 2021
Nolan Arenado, Cardinals -- 26 (11 HR, 15 2B)
José Ramírez, Indians -- 24 (13 HR, 10 2B, 1 3B)
Austin Meadows, Rays -- 24 (12 HR, 11 2B, 1 3B)
Kris Bryant, Cubs -- 19 (6 HR, 13 2B)
Marcus Semien, Blue Jays -- 18 (10 HR, 8 2B)

Arenado's at the top. Why does that matter? Because it means that this Nolan Arenado, the one on the St. Louis Cardinals, is still the old Nolan Arenado, the one who mashed with the Rockies. Not the one who slumped through all of 2020.

For Arenado, pull power is a marker. It's not a brand new development for his hitting that he's driving the ball to left field in 2021; he's always been one of MLB's most dangerous hitters to the pull side of the field. But those 26 pulled extra-base hits aren't some superfluous stat to be leading the league in. Because what was different for Arenado was 2020.

Here's how many home runs Arenado has pulled each season since the start of Statcast tracking in 2015, and his MLB rank for each year.

2015 -- 34 pulled HR (1st in MLB)
2016 -- 34 pulled HR (2nd in MLB)
2017 -- 25 pulled HR (T-7th in MLB)
2018 -- 21 pulled HR (T-14th in MLB)
2019 -- 32 pulled HR (T-1st in MLB)

2015-19 total -- 146 pulled HR (1st in MLB)

2020 -- 7 pulled HR (T-39th in MLB)
2021 -- 11 pulled HR (T-3rd in MLB)

The cornucopia of home runs to the pull field is back. Arenado has pulled all 11 of his homers in 2021, and basically, the return of Arenado's pull power means the return of Arenado, period.

So what happened last year? Well, Arenado's shoulder hurt. Arenado played through a bone bruise and AC joint inflammation in his left shoulder almost the entire season, in pain the whole time, until it finally forced him to the injured list in late September. A shoulder injury sure seems like it might affect a hitter's ability to turn on the ball and drive it.

He's healthy now, and the numbers are reflecting it -- Arenado's .514 slugging percentage and 132 OPS+, for starters, but also his batted-ball tracking data. Let's take a look at that.

• Arenado's pull rate is up, period

He's pulling over 44% of his batted balls this season, his highest in any season under Statcast tracking. He pulled just under 40% of his batted balls in 2020.

• More of his hits are to the pull field

Throw singles in there along with the extra-base hits, and Arenado leads the Majors in pulled hits overall, with 37. He's pulled 63% of his hits this season, his highest percentage under Statcast tracking. That's up from 52% of his hits a year ago.

• He's pulling more of his hard contact, too

Arenado's hard-hit balls can do the most damage when he pulls them. And he is in 2021 -- of his batted balls hit 95 mph or harder (that's Statcast's threshold for a hard-hit ball), 56% percent of them have been pulled.

That's his highest rate of hard contact to the pull field under Statcast tracking, and much more in line with his most powerful seasons pulling the ball: 2015, '16 and '19, when over half his hard-hit balls were pulled and he ended up with 30-plus pulled home runs.

In 2020, by comparison, Arenado pulled just under 45% of his hard-hit balls, more than 10 percentage points below his '21 rate.

• More of his hard-hit air contact is pulled

Hard-hit balls will get you hits, but hard-hit air balls will get you extra-base hits and home runs, and Arenado is in the lineup to slug.

This season, 60% of Arenado's hard-hit line drives and fly balls have been pulled, the highest share of any of his Statcast-tracked seasons.

• Way more of his barrels are pulled

This is a big one. Barrels are the absolute best kind of contact -- they're ideal combinations of exit velocity and launch angle, which are likely to go for extra-base hits or home runs.

Barreled balls are great no matter where you hit them. But they can be even greater when a hitter like Arenado drives them to the pull side.

Think about this: on 137 pulled barrels since Statcast started tracking in 2015, Arenado is batting .978 and slugging 3.650. That means when he barrels a ball to the pull side, it's almost always just a home run (85% of his pulled barrels since '15 have been homers.)

On 93 non-pulled barrels since 2015 -- that is, barrels hit to straightaway center or the opposite field -- Arenado is batting .785 and slugging 2.602. Still great numbers, because that's what barrels will get you, but it's a big difference between pulled and non-pulled.

In 2021? Arenado has pulled over 85% of his barrels -- 12 of his 14 total. His previous high mark for a season was pulling 68% of his barrels in 2016. In 2020, he pulled six of his nine total barrels, 67%.

So when Arenado steps to the plate, keep an eye on left field. That's where he's hitting the ball with authority, and that's going to get him his normal star slugger results, whether he's at Coors Field or Busch Stadium.