It is worth noting that in the other cases, the park was coming from a far lower prior base in terms of guest figures. Part of the reason why Nemesis and Thirteen were both able to get attendances to over 3 million could be because both 1993 and 2009 had relatively favourable guest figures up in the high 2 millions, so the park had a higher base to increase guest figures from in the first place.
Those figures suggest that The Smiler brought in around 200,000 additional guests in its opening year, which I would hardly call "little footfall" or extrapolate as meaning a lack of success or that the ride was a flop for the park. I struggle to see how 200,000 additional guests can be referred to as much other than a big success, personally.
To be honest, I think that that data shows that most of Alton's major coasters have been relatively successful at stimulating guest figure increases. If you look at it coaster by coaster:
- Wicker Man: 2017 attendance was 1,860,000, while 2018 attendance was 2,200,000. Therefore, Wicker Man increased attendance by 340,000, or 18.3%.
- The Smiler: 2012 attendance was 2,400,000, while 2013 attendance was 2,600,000. Therefore, The Smiler increased attendance by 200,000, or 8.3%.
- Thirteen: 2009 attendance was 2,680,000, while 2010 attendance was 3,080,000. Therefore, Thirteen increased attendance by 400,000, or 14.9%.
- Rita: 2004 attendance was 2,120,000, while 2005 attendance was 2,190,000. Therefore, Rita increased attendance by 70,000, or 3.3%.
- Air: 2001 attendance was 2,170,000, while 2002 attendance was 2,670,000. Therefore, Air increased attendance by 500,000, or 23.0%.
- Oblivion: 1997 attendance was 2,890,000, while 1998 attendance was 2,900,000. Therefore, Oblivion increased attendance by 10,000, or 0.3%.
- Nemesis: 1993 attendance was 2,850,000, while 1994 attendance was 3,310,000. Therefore, Nemesis increased attendance by 460,000, or 16.1%.
So if you look at that, I would hardly call The Smiler a resounding failure compared to Alton's other coasters. In fact, I'd still call it a decent success, even if not the largest success of the crop, perhaps.
Looking at that, the most lacklustre performer was actually Oblivion, which increased attendance by a relatively meagre 10,000, or just 0.3%, despite having the highest base attendance to work with from the year prior.
EDIT: It is worth noting that the post-2020 figures on that site come from a different source, the TEA index. The Merlin graph showed 2020 as being closer to 1,000,000 and 2021 being somewhere in the ballpark of 2,350,000, despite that site giving lower figures for those years. 2022 and 2023 figures from the Merlin graph are not yet available.