We'll be taking a look at the most interesting takeaways every week this MLB season so check back every Sunday for our recap. Now, here's what we learned from the last seven days in MLB:

Red Sox's title defending season officially falls apart

On Friday, the Boston Red Sox were officially eliminated from postseason contention -- less than one year after taking home the World Series title. The Red Sox's season was been full of ups and downs, starting with a concerning down at the start of the season when the club kicked off 2019 with nine losses in 12 games. Boston really never found its groove, and now the defending champions won't even get the chance to compete in the postseason. As our own Mike Axisa writes, the Red Sox are at a serious crossroads after this lost season. Not only did the club fire general manager and head of baseball operations Dave Dombrowski, but the Red Sox are also going to have to face more crucial decisions, like right fielder Mookie Betts' looming free agency. And to add insult to injury, the Red Sox are set to pay a $13.05 million luxury tax for a season where they won't play a single playoff game.

The biggest disappointment for the Red Sox this season was the starting rotation. Rick Porcello, Chris Sale and David Price all never got it going while Nathan Eovaldi was significantly limited this season because of an elbow issue. Price and Sale also missed time with injuries.

After four titles in the last 15 years, the Red Sox won't just be fighting to construct the team so it can make it back to the postseason next year, they're going to be fighting to maintain relevancy in the American League East with the Rays and Yankees closing in on strong 2019 seasons.

Yankees into postseason without pitching plan

The Yankees have managed to overcome a season filled with injuries to key players to take home their first division title since 2012 on Thursday. But, the club's "next-man up" mentality will face a real test once the postseason begins.

New York's pitching staff got a huge boost with the return of a healthy Luis Severino. Later in the week, however, right-hander Domingo German was placed on the restricted list in violation of the league's domestic violence policy and is not expected to pitch in the postseason. Plus, the Yankees lost Dellin Betances right after they just got him back, with a freak injury.

This past week, manager Aaron Boone outlined the club's postseason pitching plan, saying that the Yankees will use James Paxton as a traditional starter. But for the rest of rotation, the Yankees will mostly piggyback starters and use key relievers to finish out games. Essentially this means that the Yankees are going to just figure out pitching as they go along and make most of the in-game pitching decisions based on who they think fits best in each scenario.

It's obviously worked so far for the Yankees this season, but entering the postseason with only one reliable starting pitcher is definitely a big risk. It'll be especially interesting since the Yankees are set to face the powerful and record-breaking offense of the Minnesota Twins in the division series.

Cardinals in position to take division crown

The St. Louis Cardinals took three straight against the Cubs to start a four-game series on the road, moving the club closer to clinching the National League Central. Along with the recent success against the Cubs, the Cards also picked up a series win against the Nationals this past week. Entering Sunday, St. Louis holds a three-lead game lead over the Brewers for first place. The Cubs have fallen back six games, and are three games out of the final NL wild card spot with seven games left in the regular season.

The Cardinals have been rolling this past month (13-8 in September), and this week's only highlighted the team's strengths. One of which being the club's impressive rotation, which ranks fifth in the league (3.79 ERA) and second in the National League behind the Dodgers. Right-hander Jack Flaherty, at just 23-years-old, is enjoying a breakout season while veteran right-hander Adam Wainwright is heating up at just the right time.

In September, the Cardinals pitching staff leads the majors in ERA (2.86) and quality starts (nine). And along with the strength of their pitching, this week's also showed off the Cardinals' relentless offense. Matt Carpenter, Yadier Molina and Paul DeJong all had homers in come-from-behind wins this past week. 

The Cardinals are on the verge of clinching their first NL Central title since 2015, and they'll face the Diamondbacks and Cubs over the final week of the regular season.