Starts and Sits - All Starting Pitcher Matchups for Fantasy Baseball (September 15 - September 21)

September 20, 2025

Nick's fantasy baseball starts/sits, expert advice for all starting pitcher matchups for September 15 - September 21 (2025). Set your winning fantasy baseball lineups.

The finish line is in sight as the final two weeks of the fantasy baseball season are upon us, which we're set to crush with our starting pitcher starts/sits for fantasy baseball Week 25 - Monday, September 15 through Sunday, September 21. This column provides readers with who is pitching, the opponent, and a confidence/startability score based on an array of metrics. Keep us bookmarked for every start/sit option and two-start decision that remains between you and the championship.

For 13 years running, we have been writing this Starting Pitcher Starts and Sits series weekly here at RotoBaller. I'm Nick Mariano, and I'll take us through the 2025 season. All types of firepower go into bringing you this piece each week, as we provide a must-read series for our readers.

Newcomers should be sure to read the section below to learn the column's goal and how best to use this tool, while long-time RotoBallers can proceed to the guide. We wish you the best of luck with your fantasy baseball starting pitcher decisions, but ideally, we create our own luck with informed decision-making. September magnifies each decision, so don't take these lightly!

Start/Sit Data Overview

Ahead of each week of the fantasy baseball season, we publish the table below. We have the probable starters for every game of the week and a grade for them on a 0-100 scale. The intent is to give you advice and inspire confidence (or lack thereof) in your decisions to start or sit certain pitchers.

Please note that beyond the usual "Start" and "Sit" labels, we've expanded on the old "context-dependent" section to break it down further with "Lean Sit," "Lean Start," and true 50/50 "Coin Flip" designations. This is because different leagues call for different actions, and those in start-sit purgatory may be worth the gamble to some.

Also, we put the arms best projected to start or get bulk innings or actionable arms who may return from the injured list or be called up. Still, some situations are fluid, and we update ASAP to reflect accurate information. Rosters expanding could see teams get more bullish with bullpen games, so we'll be sure to stay on top of those assignments.

The "starts" category includes pitchers you'd likely start in every league. The "sits" are pitchers you likely sit in every league.

The 40-60 range will mean it is close, and it's up to you to decide based on your league settings or team needs (wins, strikeouts, etc.), how deep your league is, which roto/points categories are scored, and so on.

Here are your starts and sits for what we're calling Week 25 of the fantasy season and covers September 15 through September 21.

Week 25 Start/Sit Recommendations (September 15 - September 21)

Updated start/sit recommendations for this week's MLB games. This chart is updated daily as probable starters are constantly changing with postponements, injuries, etc. Scroll down further for a color-coded chart. If you can't see the chart below, click here to see the starts/sits on a separate page:

Start/Sit Color-Coded Matchups Chart (September 15 - September 21)

The below grid shows the same data but as a color-coded grid:

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