Phillies vs. Red Sox preview: How the two teams have responded since firing their managers

That TBA will be an opener for righty Brayan Bello (2-4, 7.44). Lefty Jovani Morán opened for Bello last time and the Phillies have two power lefties near the top of the lineup (Bryce Harper and Kyle Schwarber), so it's likely Morán will open again on Tuesday. Also, Thursday will be Suárez's first ever start against the Phillies. He of course spent the first eight years of his career in Philadelphia.

Here is what you need to know about the Phillies and Red Sox, and what has changed on the field since their managerial changes, ahead of this week's series.

Phillies: Better run prevention

It has certainly helped that the Phillies have played a favorable schedule. They've played the San Francisco Giants, Miami Marlins, (Sacramento) Athletics, and Colorado Rockies since the managerial change. Those four teams are a combined 17 games under .500. You can only play the schedule you're given, and wins are not assured, but the schedule has helped.

The biggest reason the Phillies have gotten their season moving in the right direction is their run prevention, both pitching and defense. Wheeler replaced the ineffective Taijuan Walker and the Phillies are doing a better job simply catching the ball. Here are the before and after numbers:

Defensive efficiency is a fancy way of saying the Phillies turned 64.7% of batted balls into outs under Thomson and 68.8% under Mattingly. The MLB average is 70%, so the Phillies still aren't even an average defensive team, but they have improved. The pitching has been much better and they're catching the ball more. That's why they're 10-3 under Mattingly.

"Obviously we started off a little sideways," Mattingly said Sunday. "But we regulated the pitching, kind of normalizing our starters, bullpen's been good. We're catching the baseball better now. The bats are getting better. I think it's kind of normalizing. It would have happened no matter what. But to happen a little faster is good."

Philadelphia's current run prevention is more in line with preseason expectations, but it's likely the real Phillies are somewhere between the 5.13 ERA team they were under Thomson and the 3.40 ERA team they've been under Mattingly. (They won't get to face the Giants and Rockies the rest of the year.) For now, the Phillies have been much better at keeping runs off the board.

Red Sox: More action on the bases

Power was a major question for the Red Sox coming into the season, one that has not been answered positively. Boston has hit 29 home runs in 40 games, the third fewest in baseball, and they're slugging .353 as a team. Only the New York Mets are worse (.341). It is really hard to score runs these days when you have to string together singles and walks.

Unless they make a desperation trade, which is not advisable, the Red Sox don't have a way to add power right now. Their roster is their roster. These are the players they have. So, what they've done is up their stolen base rate. They can't slug their way to second base, so they're running their way there. Here are the before and after numbers:

The Red Sox have the same number of stolen bases and nearly as many stolen base attempts under Tracy as they had under Cora in less than half as many games. They're stealing more efficiently too. Boston has stolen 11 bases in their seven wins under Tracy. There's a direct correlation there. When they get runners on, they take the extra 90 feet, and they scratch out runs.

"The style matches the team," Tracy said after the Red Sox stole four bases in his first game as interim manager. "We have guys that are athletic, fast. We have speed. So we can create things like we did today. We made some outs, and you know, maybe some were a little careless, but you want to be aggressive."

Given their lack of power and difficulty putting together big innings, the Red Sox have a very thin margin of error. They have to pitch well and they have to generate offense however they can. Despite that lack of power, they didn't run much under Cora. It was a very station-to-station team. Tracy has them running more aggressively and it's added a few wins to their ledger.