''This Is Us'' has become a giant of its own genre, and in terms of viewership, it's the flagship TV series of NBC network. According to tvseriesfinale.com, the hit drama's third season averaged 8.317 million viewers per episode. While this particular metric is an indication of a huge fan base if we're to compare this set of data with those from previous seasons, the blunt coldness of numbers shows a decrease of more than 25 percent in terms of viewership.

As far as the audience measurement is concerned, ''This Is Us'' has claimed a bit over the two rating point of the 18-49 demographic.

Compared to the previous seasons, that's a 34.38 percent decrease. This particular segment is where any network would look before making any future decision.

What could be the cause of 'This Is Us' viewership decline

Although the upcoming Season 4 of ''This Is Us'' is almost a certain bet, one can't stop wondering why despite all the apparent success, the show's audience has a tendency to shrink.

According to goodhousekeeping.com, the official renewal announcement for Season 4 is still pending, and that significant decline in viewership may put some worrying thoughts in the back of the fans' minds with the show currently on hiatus.

The third season had its twists and turns, its's flashes forward and sudden digressions deep into the past.

For a non-accustomed person, that fragmented narrative may be tiring. But here we're talking about people that were watching the show and then decided to let go of it. So, that argument may not suffice.

On the other side, Season 2 finale was the pinnacle of the show, especially after the whole Jack Pearson dying episode unfolded.

It was hard to match that level of intensity, especially given the trajectory the third season had.

The audience may shrink even more in Season 4

Assuming that ''This Is Us'' Season 4 will eventually get its official renewal announcement, the decline in terms of viewership may not be over. In fact, the numbers may follow a downward trend.

The reason is simple. The show's creator Dan Fogelman has already hinted on the show's future directions.

As Jack Pearson's character will most likely get less on-screen time, another male character is set to be integrated into the narrative. Entertainment Weekly reported that Fogelman said that Rebecca Pearson's father will receive a major role in the upcoming season. That could mean more digressions into the past, more backstories, and, possibly, less thrilling episodes. Basically, it'll keep up with the third season's trend.

Fogelman's attempt at trying to cover all basis and angles may keep affecting the show's viewership. As much as one would love to watch some thoroughly displayed narrative, sometimes it's better to keep it clean and simple.

Given the show's profile, going back and forth, pendulating between past, present, and future, these are inevitable acts. But that could also cause confusion, lack of engagement, and what's even worse, people deciding this show isn't worthy of their time.