MLB: Spring Training-San Diego Padres at Chicago White Sox
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Going into Wednesday's MLB slate, the Chicago White Sox are in line to be the top overall seed in the American League. Roughly 2,000 miles from Guaranteed Rate Field, the San Diego Padres have the second-best record in the senior circuit and are putting unexpected heat on the mighty Los Angeles Dodgers in the NL West. 

Not coincidentally, these are two of the most exciting teams in baseball with two of the most impressive young cores to be found. They've also taken historic leaps forward in 2020. Last season, the White Sox went 72-89, which comes to a winning percentage of .447, and finished 28 1/2 games out of first place in the AL Central. The Padres in 2019 went 70-92 -- .432 winning percentage -- and placed last in the division. Those 2019 winning percentages are notable because each team in the final days of the regular season is on pace to author one of the biggest leaps forward in MLB history. 

At this point, we are honor- and duty-bound to unfurl the relevant digits. Below you'll see the biggest season-to-season improvements in winning percentage in team history (historical data courtesy of mcubed.net): 

Team Change in WIN%

1. 2019-2020 White Sox

+22.0 (.447 to .667)

2. 1998-1999 Diamondbacks

+21.6 (.401 to .617)

3. 1945-1946 Red Sox

+21.4 (.461 to .675)

4. 1935-1936 Braves

+21.3 (.248 to .461)

5. 2019-2020 Padres

+20.8 (.432 to .640)

6. 1904-1905 Phillies

+20.4 (.342 to .546)

7. 1988-1989 Orioles

+20.2 (.335 to .537)

8. 1961-1962 Phillies 

+19.8 (.305 to .503)

T-9. 1992-93 Giants

+19.2 (.444 to .636)

T-9. 2007-2008 Rays

+19.2 (.407 to .599)

You've got some interesting clubs peppering this list. The 1999 Diamondbacks made a jump in part because of the free agent signing of Randy Johnson and the trade for Luis Gonzalez. The '46 Red Sox, who lost a taut seven-game World Series to the Cardinals, benefited from the return of a number of core performers who had been serving during World War II -- most notably, Ted Williams, Bobby Doerr, Johnny Pesky, and Dom DiMaggio. The 1988 Orioles famously started the season with 21 straight losses, but their progress the following season earned Frank Robinson AL Manager of the Year honors. The improvement of the 1993 Giants coincided with the signing of Barry Bonds. 

As for the two squadrons of note, you'll see above that the current Padres model is on pace to post the fifth biggest year-over-year improvement in winning percentage. The 2020 White Sox, meantime, are poised to set the all-time record. Let's repeat that for fitting emphasis: The 2020 White Sox, with just 12 games left on their regular season schedule, have improved their winning percentage from the prior season more than any other team in MLB history. 

Now to address the obvious qualifier. Thanks to the ongoing COID-19 pandemic -- and with assist from the dawdling of owners during negotiations with players over the structure of the season -- the 2020 regular season will span just 60 games. If you want to dismiss what the White Sox and Padres have done in 2020 relative to the other teams above, then all you need to do is point to the fact that they'll wind up playing a drastically shorter season than their fellow travelers. If that's your position, then it's a defensible one. That said, the best evidence suggests that, yes, the 2020 White Sox and 2020 Padres really are this good and would likely continue playing at their current levels. 

Bold declaration, no? Perhaps, but consider the following True Internet Facts: 

  • The White Sox's current run differential of plus-83 is tops in the AL by a huge margin. That run differential translates to a "deserved" record of 32-16, which is the same as their actual record. 
  • The Padres have a run differential of plus-81, which is second only to that of the Dodgers in the NL. That yields a deserved record of 33-17, which is one win better than their actual record. 
  • According to the BaseRuns system at FanGraphs, which evaluates how many runs a team should have scored and allowed based on their underlying fundamental indicators, the White Sox have a deserved record at that level of 33-15, which is one game better than their actual record.
  • The Padres have a current BaseRuns record of 33-17, which is likewise one game better than their actual record. 

Basically, the White Sox and Padres haven't benefited unduly from good luck this season, and if anything they've been slightly unlucky. Their success in the standings is backed up strongly by underlying indicators. Run differential and BaseRuns typically do a much better job of predicting a team's record going forward than does that team's actual current record. As such, the best guess is that the White Sox and Padres would've continued playing at this high level across the typical 162 games (barring major injuries, of course). 

Furthermore, know that the White Sox right now rank sixth in MLB when it comes to opponents' average winning percentage this season. The Padres rank 10th in that same category. So they've put together these impressive bodies of work against tough schedules.  

Whether or not you wind up acknowledging their eventual final landing spots on the rankings above, the White Sox and Padres will wind up having taken two of biggest leaps forward in living memory and beyond. And if you wish to acknowledge their places in history, then you can marshal a defense of that position based on the fact that, yes, these two teams really are genuinely great -- despite being genuinely bad not so long ago.