After much discussion, the consensus was that Darvish was tipping his pitches and the Astros had figured that out.
With the current revelations about Astros sign-stealing methods — methods that were allegedly in use during the 2017 season — Darvish posted a YouTube video discussion this and other related topics (note the Cubs cap on the table behind him):
In this Reddit thread, a user posted an English translation of Darvish’s video which is worth reading. Here are some relevant parts:
After Game 7, I’ve been personally trying to get to the bottom of this problem. This year, from a source from the Astros that I won’t disclose, I was told that I was tipping my pitches during Game 3 and 7 by fumbling my ball before my windup. Since I saw my Game 7 footage numerous times, I was convinced that I wasn’t doing that, and there was something in the back of my mind that didn’t mesh well with what that player was saying, and what was shown on the footage.
Darvish, though, went on to say that he doesn’t blame sign-stealing for his World Series failure:
Now, do I think that my failure in the 2017 WS is because of the Astros stealing signs? I don’t think so, I think Astros have talented players. Results don’t change, and I don’t expect anyone to send me apologies for what they had said to me for the past 2 years. Through adversity, I’ve been able to work hard to get to where I am, where I can play for a great organization, the Cubs. If I start associating my failure to the Astros scandal, I don’t think that I would be able to develop as a person. I think adversity is important in life, and I think these types of failures will be an important experience for me, as a player. I’m willing to swallow the results of 2017.
Darvish appears to be a great, standup guy, willing to take responsibility for his failures. He’s an easy guy to root for. But then he adds, regarding the current sign-stealing controversy:
Especially this year, I’ve noticed a lot weird things. When I’m in the set position, usually the batter looks at me. It depends on the batter, but they generally look at my elbows, my eyes, my shoulders, you know it. But several times this year, I’ve noticed that the batters don’t look at me. (Timestamp at 11:00, he does a bit of demonstration) Even without runners on second, I see players just looking into the distance, around left center field. It’s awkward. This usually happens when we’re the visiting team. I’ve even told Caratini during mound visits that the batters eyes were not on me.
That’s... very interesting. I mean, I can understand hitters looking toward a baserunner on the field for a possible stolen sign. That kind of sign-stealing is totally acceptable, it’s been going on since baseball began and is part of gamesmanship. But when you add technology:
Sign stealing is part of baseball. It’s gamesmanship. A runner picking up signs from 2nd base or looking for how a pitcher might be tipping his pitches based on how he comes set is fair game. If you can do it using your eye balls it’s ok. If you’re using technology it’s cheating.— Obi-Sean Kenobi Doolittle (@whatwouldDOOdo) November 15, 2019
Sean Doolittle is correct. And so is Yu Darvish. His video concludes, per the translation:
So… um… let’s stop sign stealing. What’s fun about swinging at something that you know that’s coming? I wonder if the batters are actually happy with that. If Houston was actually content with winning the WS knowing that they were stealing signs electronically... IDK I wouldn’t be able to do that as a player if I’m in their shoes. It’s very disappointing.
Yu Darvish has come into his own as a ballplayer, a person and a Cub. Given what he says in this video, presuming the translation is accurate, he has the chance to become one of the player-leaders in rooting out this sort of cheating.