Undefeated under Rob Thomson, the Phillies look to defy history in the NL playoff chase

Congratulations, Rob Thomson.

A week ago, nobody knew who you were. Now, the whole world knows you as baseball’s all-time winningest manager. At least, if we’re measuring by winning percentage ... and setting our minimum number of games managed at five.

Some might call that an aberration, especially if Corey Knebel keeps pitching the ninth. But, hey, 5-0 is 5-0, especially when it comes in a guy’s first five games after taking over a sub-.500 team that everybody swore was just a manager away from competence. Pity the MacArthur Foundation, because everybody in the Delaware Valley looks like a genius right now.

Given that the Phillies have been playing at a 162-win pace since making the switch to Thomson, it might be time to revisit a question that many raised when they announced Joe Girardi’s firing on Friday.

How often does a midseason managerial change actually work?

Well, I did the math — some of it, at least — and the short answer is that it depends on how you define the two parts of the question.

» READ MORE: Thomson will stick with struggling closer Corey Knebel

First, let’s define “midseason” as a juncture far enough into the schedule to give the incumbent manager a representative sample of games, but early enough that the replacement manager(s) would be in charge for a significant chunk. The MLB season can be divided into roughly four 40-game quarters, so let’s define “midseason” as the middle two quarters. Let’s also limit our study to 1996, mostly because of the questionable historical significance of the personnel decision-making of teams like the 1871 Fort Wayne Kekiongas.

Slightly more complicated is determining what we mean by the word, “work.” How do we define success? Let’s dive in.

» READ MORE: Joe Girardi struggled to trust the Phillies’ young players. Will Rob Thomson be any different?

Since 1996, the first full post-strike season and the first year in our arbitrary sample, there have been 40 instances of teams that had multiple managers finish the year with at least 40 games at the helm. Of those 40 teams, only three ended up in the divisional round of the playoffs.

Another way to read that is that only once since 1996 has a team with a losing record fired a manager at midseason and gone on to make the playoffs.

Likewise, only three teams that had a losing record at the time of their switch went on to win at least 86 games. One was that 2009 Rockies team that went on to lose to the Phillies in the NL Division Series.

The other two:

In total, nine of our 40 teams finished with a winning record, and seven won at least 86 games. But four of those seven were .500 or better when they made their change.

The Phillies certainly picked the right time to declare a fresh start. They’ve played the toughest schedule in the majors this season, according to Baseball-Reference.com. Only the Orioles have played fewer games against teams that entered Tuesday with losing records. Girardi’s team was 10-9 in those games. Thomson is 3-0.

» READ MORE: Scott Kingery is back, a year later, to help replenish Phillies’ depleted infield: ‘It’s a good feeling

After a three-game series against the first-place Brewers, the Phillies’ next 13 games will come against losing teams. They have 54 games remaining against the six NL teams that entered Tuesday behind them in the standings. They have another six against the 26-31 Diamondbacks. If they win 59% of those games — their record against losing teams to date — that’s 35 wins on top of the 25 they already have. At that point, they’d still need to win half of their remaining 48 games just to get to 84 wins. But, assuming a 38-25 record against the losing teams, even a 12-36 mark against the remainder would leave Thomson with a better winning percentage than Girardi.

Therein lies part of the difficulty in answering our initial question. You don’t get to become a big-league personnel boss without having some degree of political acumen. Clearly, it behooves somebody like Dave Dombrowski to put his new guy in a position to succeed. Many of the teams in our sample saw a modest improvement in their winning percentage after making the change. If we add them all together, the opening-day managers posted a winning percentage of .438, while their replacements combined for a mark of .480. That’s a difference of 70 wins versus 77 wins over the course of a 162-game season, well within the margin of error once we account for factors like strength of schedule and reversion to the mean.

As I wrote a couple of weeks ago, there were all sorts of indications that the Phillies would eventually start winning more games regardless of their manager.

At the same time, both history and logic suggest it doesn’t hurt to try. When the Phillies fired Girardi, they were clearly at a point where such a move made sense. But they were at that point mostly because they had tried everything else. The one possibility they had not ruled out was that a change in personality could have some positive effect on players’ ability to win their spots.

Maybe Bryson Stott had spent much of the season trying to earn his manager’s trust instead of relaxing and playing ball. Maybe Girardi’s anxiety about his job and his underperforming roster had created a negative energy that needed to be jolted out of existence.

» READ MORE: Hayes: Dave Dombrowski exterminates Phillies’ dysfunction

Whatever the case, something needed to change. Even if Thomson does not go 111-0 and the Phillies do not become the fourth team in 25 years to make the playoffs after a midseason managerial change, they’d exhausted every other option for turning things around. There was only one thing left to try.