When Mookie Betts signed his massive contract extension with the Dodgers just before Opening Day, it opened up the title of best free agent available this coming offseason.

There might not be a consensus pick, in the way Betts was. Trevor Bauer is off to a sensational start on the mound in 2020. Same for DJ LeMahieu at the plate, before he went on the injured list. Nick Castellanos is raking in Cincinnati and has an opt-out clause after this season. Others have an argument as well.

But J.T. Realmuto's case is as strong as anyone’s.

The Phillies catcher is once again making life difficult on opposing baserunners. He’s a superb athlete for his position. And so far in 2020, he’s taking his bat to another level.

Given the scarcity of all-around standouts at his position, Realmuto is looking like the most valuable player set to hit the market in November. If Bryce Harper and many Phillies fans get their way, the 29-year-old will be staying put in Philly. But since that outcome is no guarantee at this point, let’s take a look at what makes Realmuto such a special player -- and why he’s only bolstering that status this season.

Way ahead of the pack

Catching in the big leagues has always been extremely difficult but perhaps never more so than it is now. There are more pitchers than ever, throwing harder than ever, with stuff that moves all over the place. Catchers are expected to be adept at framing those pitches for strikes, in addition to blocking balls in the dirt and throwing out runners. They take a beating. And oh yeah, they still have to hit.

From 2017-19, a total of 10 catchers collected enough plate appearances in a season to qualify for a batting title. Only Realmuto did it in all three seasons, and he did it in 2016, too. Meanwhile, nobody at the position has been better. Realmuto’s 15.0 wins above replacement (WAR), per FanGraphs, in those three seasons ranked 13th among all positions players.

Most fWAR by catchers, 2017-19
1) J.T. Realmuto: 15.0
2) Yasmani Grandal: 14.0
3) Tyler Flowers: 9.1
4) Buster Posey: 8.9
5) Gary Sanchez: 8.3

What’s notable is not just that Realmuto is first. It’s also that, aside from Grandal (who landed a four-year, $73 millon deal from the White Sox last winter), nobody else is anywhere close. Of the 45 position players to crack 10 WAR over those three seasons, only those two (4.4%) spent the majority of their time behind the plate.

And Realmuto isn’t slowing down. Through the Phillies’ first 18 games of 2020, he’s already reached the 1-WAR mark, putting him among the MLB leaders. One reason? The increased thunder in his bat.

He’s bashing the ball like never before

Realmuto has been an above-average hitter in every season since 2016, with a combined 115 wRC+ that ranks as elite for a catcher. But he put up those numbers without being a standout in any one area.

He hit for a solid average, drew just enough walks and hit for decent power, finishing with 21 homers in 2018 and 25 last year. In ‘19, his hard-hit rate put him in the 62nd percentile, and his barrel rate in the 59th percentile of MLB hitters. In ‘20, though? Things look a bit different.

Realmuto is swinging and missing a bit more, and the same goes for strikeouts. But the trade-off has been worthwhile -- as seen in his .288/.338/.682 (166 wRC+) line.

His 46.8% hard-hit rate is a career high. Among the nearly 200 batters with at least 40 batted balls through Monday, only eight had converted more of those into barrels -- the highest quality of contact -- than Realmuto (18.6%), who sat between Mike Trout and Aaron Judge in the rankings.

Largest increases in barrel rate, 2019 to '20
Min. 200 batted balls in ‘19, 40 in ‘20 (through Monday)

1. Corey Seager (LAD): +13.0% (up to 20.3%)
2. Brian Goodwin (LAA): +11.5% (up to 17.8%)
3. Colin Moran (PIT): +11.2% (up to 18.6%)
4. Nick Castellanos (CIN): +11.1% (up to 22.0%)

5) J.T. Realmuto (PHI): +9.9% (up to 18.6%)

As a result, Realmuto already has eight homers, or almost a third of the way to last year’s career-high total. The only other players in Phillies history with at least eight homers in the team’s first 18 games of a season are Mike Schmidt (12) in 1976 and Cy Williams (eight) way back in 1923. Meanwhile, Todd Hundley (1996) is the only other Major Leaguer to have homered as many as eight times in his team’s first 18 games, while playing catcher, since the legendary Yogi Berra for the 1956 Yankees.

There is certainly reason to question whether Realmuto can sustain such a big power gain while also hitting more than half his batted balls on the ground. But by crushing the ball when he does lift it, he’s gotten off to an MVP-caliber start.

Don’t forget his sensational glove

The big bat has taken Realmuto to another level this season, but what he does behind the plate is still his calling card.

Statcast began tracking in 2015. Fortuitously, that was when Realmuto played his first full season. Sufficient data is not yet available for 2020, but we’ve already been able to see that he’s among the very best annually when it comes to pop time.

Realmuto’s average pop time to 2B by season
With MLB rank (minimum 20 attempts)
2015: 1.93 seconds (T-2nd)
2016: 1.92 seconds (T-3rd)
2017: 1.90 seconds (T-1st)
2018: 1.90 seconds (1st)
2019: 1.89 seconds (1st)
MLB average: 2.01 seconds

Realmuto also ranked second last season among catchers in average arm strength on max-effort throws (88.2 mph), helping him throw out 43 of 92 basestealers (46.7%). Not only did that percentage rank first in the Majors, but because opponents continued to test him, Realmuto erased 16 more runners than any other catcher. He’s at it again early in 2020, throwing out four of eight runners (50%) attempting to steal.

Realmuto’s arm has always been dangerous, but his improvement as a receiver has been huge as well. Statcast measures how often catchers get called strikes on pitches taken around the edges of the zone, and translates that rate to runs. From 2015-16, Realmuto’s framing cost his team 18 runs; since then, it’s gained them 17 runs. Last season, Realmuto tied for sixth among MLB catchers, at +8. Early in 2020, he’s in the top five in strike rate on those borderline takes.

And he can run, too

Catchers are slow, almost as a rule. Realmuto is the exception to that rule.

Realmuto has had an average sprint speed, per Statcast, between 28.6-28.8 ft/sec in each full season of his career (it’s at 28.0 ft/sec early in 2020). That’s good for anyone. MLB average is 27.0 ft/sec, and Realmuto has ranked in at least the 86th percentile of all players in each of those years. For a catcher, though, it’s almost off the charts.

Of the 53 catchers with at least 250 qualifying runs since 2015, the only backstop in his vicinity is Jorge Alfaro. (Coincidentally, the Phillies sent Alfaro to the Marlins as part of the trade for Realmuto in February 2019).

Realmuto even swiped nine bases in 10 tries last season, and he’s been far and away the game’s most valuable baserunner at a position in which almost nobody is a positive.

Top catchers by FanGraphs baserunning value
Since 2016
1) J.T. Realmuto: +13.3
2) Chris Herrmann: +5.0
3) Blake Swihart: +2.3
4) Luke Maile: +1.7
5) Andrew Knapp: +1.6

So when it comes to catchers, Realmuto is MLB’s best baserunner and best thrower. He’s grown into one of its best receivers, and after already establishing himself as one of its best hitters, he’s ramped up his power output to an elite range early in 2020. Simply put, Realmuto is an all-around star at a position where that is a true rarity.

Now he’s set to hit the open market -- if the Phillies let things get that far.