I can, I think, explain some of this. Nick Markakis isn’t on the Braves’ roster – he could still wind up back there – and the difference between Markakis and, say, Adam Duvall off their Braves’ numbers last year is a net loss of 3.1 in FanGraphs WAR. Swapping out Kurt Suzuki for Brian McCann dings them another 1.5 of fWAR. Losing Anibal Sanchez – he, like Suzuki, signed with the Nats – is a loss of 2.4. Going by fWAR, Sanchez was the Braves’ second-best pitcher last season.
Adding the Josh Donaldson of any year from 2013 through 2017 would have given the Braves a major WAR bump, but the Donaldson of those years isn't all the spreadsheets see. They also see a 33-year-old coming off his worst year -- injuries had much to do with it -- since he established himself in the majors. FanGraphs projects Donaldson at 4.1 WAR this season, which is still very good, but he had a five-year run where his worst yield was 5.1. (His best was 8.7 in 2015. He was the American League's MVP.)
The creeping sentiment among the sabermetric set is that the Braves haven’t done enough, acquisition-wise, to keep pace with their neighbors. The Nats signed Patrick Corbin, the biggest-ticket free agent among pitchers, to go with Sanchez and Suzuki. The Mets traded for Robinson Cano and closer Edwin Diaz. The Phillies landed Andrew McCutchen and shortstop Jean Segura; they also bettered their bullpen with David Robertson. (They’re also expected to land either Harper or Manny Machado.)
What this ignores is the Braves' youth. Ronald Acuna and Ozzie Albies and Johan Camargo have enough of a track record to factor into the analytic forecasts, but can we put a ceiling on any of the above? Analytic forecasts – Baseball Prospectus' much-loved PECOTA won't be available until February – tend to flatten toward the middle. FanGraphs' projections have Acuna at a 3.3 WAR for 2019; he had a 3.7 over 111 games last season. He could double that 3.3 and nobody would be shocked.
This time a year ago, the esteemed Joe Sheehan cited the Braves' Vegas number of 73.5 wins as an "over" pick. This year, he writes, he's liking the over on the Braves at 84, but he notes that this "fall(s) below the level of a full recommendation." Even for someone like Sheehan, who saw the Braves coming, there's a bit of hesitation.
The Braves didn't need to win this offseason to win the East again. They might, however, need to do a bit more than they've done.