Ronald Acuña Jr. may be the early National League MVP Award frontrunner, but he’s not the Braves’ only top MVP candidate.

As of Friday morning, Atlanta employs the NL leader in wins above replacement (per FanGraphs) among position players and the MLB leader in expected wOBA (based on quality of contact, K’s and BB’s), but it's not Acuña.

• Teammates to finish 1-2 in MVP voting

The superstar outfielder is close, but he trails Braves catcher Sean Murphy, who has made a bigger impact than any other offseason acquisition so far in 2023.

Highest fWAR total among players who changed teams after 2022:

• 1. Sean Murphy (ATL): 2.3
• 2. Nathan Eovaldi, (TEX): 2.2
• 3-T. Xander Bogaerts (SD): 1.7
• 3-T. Brent Rooker (OAK): 1.7
• 5. Dansby Swanson (CHC): 1.6

Atlanta had one of the most productive catching tandems in the game last season, with Travis d'Arnaud and William Contreras combining for 38 homers, 105 RBIs and an .823 OPS over 802 plate appearances.

Nevertheless, the Braves saw an opportunity to upgrade at the position and took it, dealing six players to acquire Murphy from the A's this past December in a three-team trade that also involved the Brewers. Murphy was already controllable through 2025, but the Braves quickly signed him to a six-year, $73 million extension through 2028.

He’s helped his new team post the best record in the NL (25-13) through Friday. The NL East was expected to be one of the tightest division races in baseball, but Atlanta has opened up a six-game lead.

• Watch Murphy's 2023 highlights

There are few players more valuable to a team than an elite two-way catcher, and Murphy has been just that in 2023. He’s always been a strong defensive backstop, and this season has been no exception.

Murphy does everything well behind the plate (all stats below are through Thursday):

• Framing: He has the fourth-highest strike rate on borderline pitches and is tied for first in framing runs saved in 2023.
• Blocking: He’s tied for ninth in blocks above average in 2023 and is tied for third since 2020.
• Controlling the running game: He’s tied for fourth in pop time on steal attempts at second base, ranks sixth in catcher arm strength and is tied for sixth in caught stealings above average in 2023.

Thanks in part to Murphy’s defensive prowess, the Braves have allowed the second-fewest runs per game in the NL despite dealing with injuries to Max Fried, Kyle Wright and Raisel Iglesias.

Meanwhile, he’s hitting like Mike Piazza in his prime, leading the NL in slugging (.613) and OPS (1.040) while producing nine homers and 32 RBIs in 33 games.

Murphy has made 29 appearances as a catcher this season and owns a 1.131 OPS in these games, one of the best starts to a season any catcher has had.

Per Stathead, it’s the seventh-highest OPS anyone has recorded through 29 games as a catcher in the expansion era (since 1961).

Highest OPS as a catcher through 29 games, expansion era:

1. Joe Mauer, 2009: 1.225 (won AL MVP)
2. Mike Piazza, 2000: 1.196 (third in NL MVP voting)
3. Mitch Garver, 2019: 1.158
4. Mike Piazza, 1995: 1.155 (fourth in NL MVP voting)
5. Ted Simmons, 1977: 1.148 (ninth in NL MVP voting)
6. Dick Dietz, 1970: 1.142
7. Sean Murphy, 2023: 1.131

Murphy was an above-average bat during his time with the A’s, recording a 115 OPS+, but this is a new stratosphere for him.

Getting away from the pitcher-friendly park factors at the Oakland Coliseum has certainly helped. During his time with the A’s, Murphy posted a .684 OPS over 162 games in Oakland, compared to an .820 OPS everywhere else. He’s put up a .963 OPS in 18 games at Truist Park this season.

However, that’s hardly the only reason behind Murphy’s offensive breakout. He’s made several notable improvements in 2023:

1) He’s being more selective: Murphy is swinging less overall this season, going from an above-average swing rate in 2022 to a below-average figure in 2023, and he’s showing much better plate discipline.

His chase rate is 24.6%, down 4.9 points from 2022, which has led to a significant uptick in his walk rate -- from 9.2% to 15.2%.

2) He’s destroying four-seamers: Pitchers have had a tough time getting a four-seam fastball by Murphy this season. No hitter has a higher slugging percentage on four-seamers (min. 20 PAs ending on four-seamers) than the Braves catcher, who is slugging 1.087 with a .478 batting average against them.

Amazingly, eight of the 17 batted balls he’s produced on four-seamers in 2023 were barrels, batted balls with the optimal combination of exit velocity and launch angle, typically resulting in extra-base hits.

Murphy had success against four-seamers prior to this season, but nothing like this.

3) He has the lowest oppo rate of his career: As the spray chart of Murphy’s career extra-base hits shows, the catcher does most of his damage when he hits the ball either to his pull side or straightaway.

Murphy has practically eliminated batted balls to the opposite field in 2023 -- he’s gone oppo on only 10 of his 82 batted balls (12.2%), one of the lowest rates in MLB. Meanwhile, he’s hitting .417 with an .889 SLG when he pulls the ball or hits it straightaway.

As you might expect based on his performance, Murphy is also producing more quality contact, in terms of exit velocity and launch angle. His average exit velocity is up 3.9 mph, his hard-hit rate is up 6.7 percentage points, his sweet-spot rate is up 5.5 points and his barrel rate is up 11.5 points since 2022.

Murphy’s advanced hitting metrics sum up just how great he’s been this season:

• His xwOBA ranks in the 100th percentile (80th in 2022)
• His xSLG ranks in the 100th percentile (76th in 2022)
• His xBA ranks in the 97th percentile (63rd in 2022)
• His barrel rate ranks in the 98th percentile (74th in 2022)
• His hard-hit rate ranks in the 81st percentile (59th in 2022)
• His walk rate ranks in the 94th percentile (63rd in 2022)

If he keeps this up, the race for the NL MVP between Murphy and Acuña could wind up being much closer than the one for the NL East title.