Despite having what some critics have called Downton Abbey‘s weakest season, ratings are still huge for PBS Masterpiece and have showed only a fairly modest decline since the drama’s return several weeks ago.

And despite having what might be Sherlock‘s strongest season yet, ratings are still less than half of Downton Abbey‘s performance and dropped more than one might expect for the second episode.

What gives?

Sunday’s Downton averaged 8.2 million viewers and Sherlock was seen by 2.9 million viewers. Both had stiff competition against the Grammys and football. Yet Downton has fallen a reasonable 20 percent over four episodes, while the Sherlock numbers represent a decline of 28 percent from just last week’s premiere.

Some extra drop-off was to be expected since the Sherlock premiere was hugely anticipated to solve season two’s big cliffhanger, yet it’s still surprising that the show’s audience is not bigger overall this season, and for a few reasons: There’s been a hugely rising buzz for Sherlock over the past couple years since season two aired, partly thanks to the profiles of stars Benedict Cumberbatch and Martin Freeman; the new episodes received strong advance reviews from UK critics and fans, and the show was paired with Downton originals for the first time, giving the detective drama a big lead-in. Plus, duh, it’s just a wonderful show. If you were checking Twitter last night, you would think half the Internet was watching Sherlock.

There’s some savvy comments below about the fact PBS is airing Sherlock pretty late at night (a 90-minute show that starts at 10 p.m. requires some commitment) and that many U.S. fans illegally download Sherlock ahead of the U.S. premiere (and because Dowton skews older, and is less prone to piracy). Both are surely factors that reduce PBS’ reach … yet 2.9 million still feels smaller than it should be given all the factors above, and doesn’t explain why the show dropped by nearly a third week to week.

Meanwhile, DVR numbers were just released for the Downton season four premiere. The episode grew by 52 percent to a tea-and-crumpet-worthy 15.5 million.

Here are EW’s recaps for last night’s Downton and Sherlock.