Even prior to the Season 3 finale of The Flash, speculation has been tossed around that The Thinker will be the big bad for Season 4. He has to be right? We've had too many winks at this point for it to be anyone but. Essentially, if The Flash Season 4 villain isn't The Thinker, then WTF was all this evidence pointing toward otherwise?
First, Andrew Kreisberg flat out stated the Season 4 villain of The Flash is not a speedster. Now, that may seem like a short list given the history of big bads we've seen on the show thus far, but it's actually longer than you would think. The Flash has many enemies who aren't speedsters worthy of a full season, and we've already met a bulk of them, save a few. Unless The Flash is planning to go full Crisis On Infinite Earths on us, I think we can rule out Anti-Monitor, which leaves Clifford DeVoe aka The Thinker as one of the biggest Flash villains who still has yet to make an appearance.
In person at least; as fans of The Flash know we've heard his name before. Our first mention of The Thinker came via a previously speculated big bad for Season 4, Abra Kadabra. While mentioning he was from the future, Abra Kadabra casually rattled off a laundry list of villains that proved to The Flash he knew his secrets. Simply mentioning The Thinker by his last name DeVoe, Abra Kadabra ended with his name on a list that included Reverse Flash, Zoom, and Savitar. If The Thinker is a one off villain, it would be more than a little weird that he's relevant enough to be mentioned on a list of major baddies.
That wouldn't be the first time Clifford DeVoe would find his name on the lips of a villain, either, as Savitar mentioned him in the Season 3 finale. While Barry tried to reason with his time remnant, Savitar mentioned The Thinker by referencing a cerebral inhibitor team Flash constructed in an effort to stop him. While that again served as a clue that DeVoe is probably the next major villain in Season 4 of The Flash, it also solidified another fact that may not be so obvious.
The mentioning of the cerebral inhibitor would appear to confirm that the DeVoe mentioned in The Flash is, in fact, the same Clifford DeVoe who is known as The Thinker in the comic franchise. That may seem a bit of a no brainer to most, but those who watch Arrow know that just because someone is named after someone in the comics, that doesn't mean that's who they are in the show. Of course, Savitar also added the line, "you haven't gotten there yet," to inform both Barry and fans that they didn't miss an episode or anything. The writers for The Flash really seem to have a love of foreshadowing things!
So yeah, I think it's pretty clear that The Thinker is the Season 4 big bad on The Flash. If not, then he has a killer agent to be able to get more hype than whoever will actually become the big problem for the team in Season 4. We'll know for certain when The Flash returns in the fall on The CW. Bide your time for the return by binging on new shows and ensuring your favorites are safe for next season.