The Boston Marathon is not kind to reputations. The unbeaten and the seemingly unbeatable have been humbled here, and the last pre-race favorite to win the men's race was Robert Kipkoech Cheruiyot in 2008.
The elevation profile of the course -- which cossets and then tortures you -- the possible extremes of weather and wind and race policy prohibiting pace-setters combine to create high levels of unpredictability.
With that in mine, here are some things to look for in the men's elite race.
Dennis Kimetto's tactics
A huge talent and proven winner, Kimetto emerged in 2011. He's 30, but is still young in marathon terms and could be capable of improving even the near-world record 2:03:45 he ran while winning Chicago last October.
Kimetto a close friend and training partner of Geoffrey Mutai, who ran the world's fastest time -- 2:03:02 -- in the wind-aided Boston race in 2011. Together the pair leads and sets the training for a whole group in Kapng'etuny, Kenya.
Kimetto has said his ankle and recent hamstring problems are clear, and his "training is OK." The main unknown is his ability to race without the pacers he has employed in his three marathons to date: Berlin 2012, when he was second to Mutai in 2:04:16; Tokyo in 2013, when he was first in 2:06:50; and the Chicago win.
Watch Kimetto's positioning in the pack, and whether he figures out how to handle Boston's quirky gradients.
Lelisa Desisa's inspiration
"It is especially significant to win again this year. Last year I was at first so happy that I won, then so saddened at the terrible thing that happened. I donated my medal to Boston, but now I truly want to win another medal here. It is important to me after last year. The opposition is so strong I cannot be sure, but my training is very good," Desisa said through an interpreter.
Boston has always been a race with extra meaning, since Stylianos Kyriakides won "for Greece" in 1946 and especially so this year.
Desisa's remarkable year in 2013 showed he can perform on any course and under any conditions. His fastest time was 2:04:45 in winning Dubai in January. Then came his 2:10:22 win in perfect conditions at Boston and a 2:10:12 that earned a silver medal in oppressive humidity at the World Championships in Moscow in August.
He is becoming known in America, too, having won at the Cooper River Bridge Run, Cherry Blossom 10-Mile Run and Utica Boilermaker 15K. Look for Desisa to follow and, as he said, "watch them." His move could come down the stretch coming on to Boylston Street and end with a doubly emotional finish if he gets there first.
Micah Kogo's hill running
England's Mo Farah showed in London that the transition from track superstar to marathon winner is not an easy one. Micah Kogo was slightly less stellar than Farah on the track, but he's an Olympic bronze medalist at 10,000 meters and has a blazing 26:35.63 best at the distance. And running track gave him so much tactical experience that he will not to be intimidated.
"I am used to running with the big names -- [2014 Paris winner Kenenisa] Bekele, [Ethiopian legend Haile] Gebrselassie -- I cannot be scared," Kogo said.
Kogo's marathon debut was last year's Boston, when Desisa got away in the last mile. Given Kogo's track speed he could have been expected to take over when still in contention so late in the race, so did he make a mistake?
"It was not a mistake. It was my first marathon, and I was not confident. I knew nothing about marathons. Still so far from the finish, when he made his move, I could not go with (Desisa)," Kogo said. "Now it is my second time at Boston, and I have improved. I know it is a tough course, and I have trained many times on a course at home in Kenya that is like Boston, with the same hills.
"The Boston Marathon is not an easy course. It is downhill and uphill, but because I have been here once, I am more confident."
Like Kimetto, Kogo trains with a high-level group, "including some strong guys." When pressed, he defined "strong" as a 2:06 marathon. Only in Kenya.
Keep an eye on Kogo's increased confidence on the hills, and for him to try to stay close enough to use his track sprint in the last 50 yards.
The second-string guys
You can learn a lot from the lesser-known runners who sit at the edge of the elite tables and are largely overlooked by the media. You learn that they may become more than just a supporting cast.
That group includes runners like Frankline Chepkwony, another member of the Mutai/Kimetto training school.
"In training, it is Geoffrey, Dennis, and me, together. I think now I am as good as Geoffrey. With Dennis, I ran a hard 38K, and we were together. In July last year, I ran a half-marathon in France, on a very hilly course, like Boston," Chepkwony said.
That half marathon was a win at Boulogne in 1:00:11. With a PR of 2:06:11 in 2012 and a 2:06:59 win at Seoul in 2013, Chepkwony has the firepower to win.
Markos Geneti also bears watching. Geneti was overshadowed by his training companion Desisa last year in Boston, when he finished sixth in 2:12:44. Geneti has a best of 2:04:54 (Dubai, 2012), though, and the speed of a world indoor 3000-meter medalist (bronze, 2004).
The amiable and modest Gebre Gebremariam was third in Boston last year, though he is probably now fading.
"We train together, Lelisa, Markos, and me. Markos is very strong. I am in shape but have some problems," said Gebremariam.
Then there's Ethiopia's Tilahun Regassa, too fast to be forgotten after running 2:05:27 to finish third at Chicago in 2012 and 2:05:38 in winning Rotterdam in 2013.
"I will wait till 25K and then decide if I should push. We test there. Then I will not wait for the sprint. I will try my best from 5K out," said Regassa.
Wilson Chebet is also someone to keep an eye on. "Mr. Amsterdam" as the Kenyan is known, having won that marathon three times, also has a victory in Rotterdam in 2011 with a PR of 2:05:27. Fifth at Boston in 2012 in a modest 2:14:56, Chebet has something to prove.
Be sure to look for Ryan Hall, too. You won't have to look hard, though, because Hall has every intention of being extremely visible.
"You will definitely see me. I'll milk the crowd from the beginning. I'll run on the excitement. There'll be a ton of crowd support, an electric atmosphere. Will I lead? Not all the way, but I'll be a factor. I love to lead. I like to mix it," Hall said.
"I love this course, it's super technical and I know how to work it. I've trained on a treadmill that simulates the Boston course. Do I need to win? I'd be okay without it, life isn't about winning everything you want, but I believe that some day I'll win Boston."
And watch out for other Americans. Jason Hartmann has two fourths to his credit in Boston, but runs so astutely that you have to wait a while to notice him despite his height. Brett Gotcher is making his Boston debut and will be hoping to recapture the form that carried him to fifth place in the 2012 US Olympic Trials. As for Abdi Abdirahman, he's philosophical about the superior PRs of the Ethiopians and Kenyans.
"It will be man-to-man, macho man, there is no pace maker, it depends on who takes it out. I think it goes out conservatively for the first 13 miles. I think the race will be between the 13- and 21-mile marks," said Abdirahman. "The end is going to be tough. The strong survive. The Boston course, people say it is a course that beats you up. The best man, the last man standing, will win."
The last word belongs to Meb Keflezighi, the elder statesman of the American marathoners but one who can't be discounted in a big race. After all, who else from the 2004 Olympics is still a factor at this level? Who else in the field was on the Boston podium (third) back in 2006, when Desisa was 16 years old? Like Abdirahman, Keflezighi takes heart from the fact that Boston is about racing, not time-trials.
"Boston is all about the title. There is no time. Hopefully, an American can come out on top but at the same time, you can't play defense. You have to dictate and adapt, you have to change your mind. Tactics. Tactics. Tactics," said Keflezighi.
"It is going to feel like it did in 2006. I ran 1:02:44 halfway, which was a world record at that time. I look at the overall time and I said, 'it is going to be a fast day, or it is going to be a long day.' And it was a long day. People make mistakes and I made my mistakes. That was probably my best time to win it.
"I think the race will be determined from (mile) 17, where you make the right turn at the fire station and after that going up the hills. After 22, they will have that energy of the crowd. I want to be in the mix. They try to break you down. Hopefully, I'm not broke down at that point," said Keflezighi.
Some 36,000 other runners will be hoping for the same thing on Monday.