There's only so much you can take from the first day or two of baseball. There's so much more to come; we're not even 1 percent of the way through the season. Javier Baez probably won't hit the 324 home runs he's currently on pace for. Luke Voit isn't going to hit 1.000. It's not even April yet. Even when it is April, it's still early -- as the 11-1 start from last year's Mets would remind you. It's so, so early.

You know all this by now. You know the phrase "small sample size" and how any reactions to a day or two of baseball are probably overreactions. But the hesitation to try to glean some knowledge from the first real baseball in months is nearly irresistible, not to mention that when you're measuring skills, such as speed and arm strength, you don't need a large sample. (You can't fake those kinds of abilities, even for a day.) So, let's ask the question: What have we learned so far, if anything?

Maybe nothing. Maybe something.

1) Kris Bryant's shoulder might be feeling fine.

As was endlessly reported in 2018, Bryant's second-half power slide was largely attributed to a sore left shoulder, injured on a headfirst slide in late May. Around a pair of trips to the injured list, Bryant saw his season collapse.

Through May 31, Bryant was hitting .286/.401/.524, with a strong 39 percent hard-hit rate. From June 1 on, Bryant hit .260/.348/.400, with a well below-average 27 percent hard-hit rate. It's not hard to see the difference, right?

Bryant didn't have surgery, and spent all winter saying that his shoulder would be sound. On Opening Day in Texas, Bryant made contact in four of his five plate appearances, including his first homer of the season. More important, for our purposes, is how hard he hit the ball.

• 111.2 mph -- flyout (first inning)

• 85.8 mph -- groundout (fourth inning)

• 97.1 mph -- groundout (fifth inning)

• 104.6 mph -- home run (eighth inning)

That's three balls hit at 97 mph or more, something Bryant did six times in a single game in the first two months of 2018 ... and just once after. Even that one time was on June 15, meaning that in the first day of 2019, Bryant did something he didn't do even once in the final 3 1/2 months of 2018. It doesn't guarantee the shoulder is good and healthy, but it's absolutely a good sign.

2) Fernando Tatis Jr. can really, really run.

We knew that already, obviously. MLB Pipeline gave Tatis a 60 run tool on the 20-80 scouting scale, and he stole 32 bases in the Minors in 2017. The eye test usually works pretty well when it comes to speed, but lots of guys are fast, and when the 20-year-old Tatis made his Major League debut on Thursday, it gave us a chance to see just how fast he is.

In the fifth inning, he laid down a bunt against Madison Bumgarner, beating out the throw from third baseman Evan Longoria. That gave us the opportunity to track two important speed-based numbers: 30.1 feet per second and 3.82 seconds. They're both fantastic.

The first, 30.1 ft/sec, is Tatis' Sprint Speed, where 27 ft/sec is "average" and 30 is so elite that we created a separate definition just to track them. It's not that getting to 30 ft/sec is so rare, because we saw it a dozen times on Opening Day. It's that the players who can get there are elite speedsters. Among those who did it on Thursday: Harrison Bader, Byron Buxton, Adalberto Mondesi, Amed Rosario and Billy Hamilton. So, too, did Tatis.

The second, 3.82 seconds, is Tatis' home-to-first time. It was tied with Hamilton for the fastest time of Opening Day. In 2018, only three Padres (Cory Spangenberg, Travis Jankowski and Manuel Margot) pulled off a 3.82 or better. It doesn't take a whole lot of time to see if a guy has wheels, and Tatis made it clear on day one that he does.

3) Mike Trout and Bryce Harper have stronger arms than you remember.

You think of Trout as being the best player alive, the man who can do anything, though his arm has generally been considered the weakest of his five tools. You think of Harper as being -- when it's all clicking -- the lefty masher who can anchor a lineup, as Philadelphia hopes he can do for the next 13 years, even if his defensive metrics told a lesser story in 2018.

So we'll admit to some amount of surprise when we looked up the top of the Statcast outfield arm strength leaderboards on Opening Day and found Trout and Harper listed as 1-2, owners of the only two tracked throws of 90 mph or more.

• 96.1 mph -- Trout, on Chad Pinder's second-inning sac fly

• 94.3 mph -- Harper, on Nick Markakis' second-inning single

Neither throw prevented a run from scoring, though Harper's accurate laser to the plate allowed J.T. Realmuto to then throw out Markakis trying to reach second base. But they did show that these two stars still have the cannons you don't often think about, when they need them. Trout's 96.1 mph would have been his fourth-hardest throw of 2018; Harper's 94.3 mph would have been his sixth-hardest.

4) We might be seeing more of the pivot away from fastballs.

In February, we wrote about trends to watch in 2019. One of them was that fastball usage (especially sinkers) might continue to decrease, as breaking pitchers (especially sliders) could increase. We cannot stress enough that a day or two of baseball is not enough to prove or disprove that theory. That said, it was interesting to see how a few notable starters approached their first game of 2019.

For example, take Jordan Zimmermann, who had one of his best starts in years on Opening Day, retiring the first 20 hitters he saw and ultimately allowing just one hit in seven innings against the Blue Jays. It's not that he was throwing hard, averaging 90.9 mph on his fastball. It's that, of his 70 pitches, only 25 of them, or 35.7 percent, were fastballs. The rest were overwhelmingly sliders and curveballs.

If we go all the way back to 2012, the first year Zimmermann threw enough innings to qualify for the ERA title, that 35.7 percent fastball rate was the lowest of any of his 201 starts. It was satisfying to see, because Zimmermann showed up on our list of pitchers from last year who should go all-in on the breaking-pitch trend to hide unimpressive fastballs.

He wasn't alone. Here are all of the starters who had notably low fastball (defined as four-seam, two-seam, or sinker) percentages in their Opening Day starts.

• 35.7 percent -- Jordan Zimmermann, lowest in any 2012-19 start

• 31.5 percent -- Madison Bumgarner, 17th-lowest of 253 career starts

• 45.5 percent -- Julio Teheran, third-lowest of 194 career starts

• 45.5 percent -- Max Scherzer, 12th-lowest of 330 career starts

• 45.8 percent -- Jameson Taillon, lowest of 76 career starts

• 47.3 percent -- Luis Castillo, second-lowest of 47 career starts

• 49 percent -- Jose Berrios, lowest of 72 career starts

An early March blip? Perhaps. A continuation of a trend? For some guys, almost certainly.

5) Some of the non-closer relievers we've been pumping up are still very good.

In the age of Andrew Miller, perhaps it shouldn't be surprising that non-closing relievers can be stars, too. We've been talking about a lot of the lesser-known names to watch all for months now, including features on Ryan Pressly, Adam Ottavino, Taylor Rogers and longtime Statcast hero Seth Lugo.

All four pitched on Thursday, and the results were stunning. The quartet faced 15 hitters, and combined to strike out 11 of them, without a walk. (That's a 73.3 percent strikeout rate, if you're scoring at home.) They allowed just one hit, a softly hit Tommy Pham single off Pressly.

Individually, it looked like this:

• Pressly: four batters faced, two strikeouts, one single

• Rogers: four batters faced, three strikeouts

• Ottavino: four batters faced, three strikeouts

• Lugo: three batters faced, three strikeouts

Rogers, remember, hasn't allowed a run since last July 28. He extended his scoreless appearance streak to 29 games by nailing down Minnesota's season-opening victory against Cleveland.

They weren't the only ones, obviously. Ken Giles struck out all three hitters he saw, as did Joe Biagini and Nick Burdi. There's a near-endless amount of quality relievers these days. These are the four who have really stood out to us in terms of raw ability in the past, however, and the four we expected monster 2019 seasons from. So far? So good.

6) There are going to be so, so many homers, again.

We'll accept that the Dodgers aren't going to keep hitting eight homers every night, so take their skewing impact on this with the large grain of salt it assuredly requires. But in the first hours of the 2019 season, we saw 46 home runs -- which is tied for the most all-time in season-opening games with one of the most offense-friendly seasons ever.

• 46 homers -- 2019
• 46 homers -- 1999
• 42 homers -- 2000
• 41 homers -- 2010

(Note that we're looking at each team's first game, so this includes the Mariners and Athletics from their first tilt in Japan, not their games on Thursday. That actually undersells this, because the Mariners hit two homers on March 20, but five on Thursday off the Red Sox.)

Twenty different teams homered in their first games. Perhaps not unrelated, however: the Majors combined to hit .204 in their Day 1 games. That's the lowest since 1943, and the third lowest of all time. Batting average isn't a good indicator of offense, obviously, and this year's Day 1 OPS of .673, thanks to all the power, was actually a middle-of-the-pack mark, 69th of the 112 years where such data exists. High power, low batting average? Sounds like modern-day baseball.

7) Bumgarner may be San Francisco's biggest slugger.

In the third inning of San Francisco's 2-0 loss to San Diego, Bumgarner stepped up and smashed a 106.1 mph line drive off of Eric Lauer. It went right to left fielder Wil Myers for an out, but more importantly, it was the hardest-hit ball of the day by any Giants hitter. Bumgarner, you may remember, is a pitcher, and this is actually the fifth time he's had the hardest-hit ball for the Giants dating back to 2017.

We'll defer on the question of whether this says more about the famously hard-hitting Bumgarner, who has 17 career home runs, or the light-slugging Giants lineup that sets up around him. But know this: The pitcher who has had the second-most games atop their team's hard-hit leaderboard is ... Bumgarner's San Francisco teammate Jeff Samardzija, tied with Noah Syndergaard. He has a career line of .127/.147/.197 (with, to be fair, three home runs).