"Desire hath no rest, is infinite in itself, endless, and as one calls it, a perpetual rack, or horse-mill." - Robert Burton, The Anatomy of Melancholy

Mike Trout is amazing. People joke that Trout gets too many articles written about him, but really, there aren't enough articles about him, not when you stop and think about how truly and unbelievably good he is as a player. He's the best baseball player of the last several generations, and yet we pay close attention to him only when someone identifies a (temporary) weakness and he gets slightly worse, or he somehow steps up his game and gets even better. The rest of the time? It's just Mike Trout, 24-year-old god-king of baseball. No big deal.

Jeff Sullivan has talked about this a lot: how fans in general are just astoundingly ungrateful for the incredible players we have when those players aren't new. I know for a fact I do this too; as soon as an incredible performance is expected, I'm not excited by it anymore.

This is something I think about a lot, and this week, I learned it's the product of a real, known psychological concept: the hedonic treadmill. I am emphatically not a psychologist, so if I misstate anything, I'll let Russell Carleton correct me, but my understanding of the idea is that humans adjust very quickly to good or bad life events and thus maintain a fairly stable level of long-term happiness. Something great happens to you? Great! You'll be happy about it, until you get used to it, at which point you probably won't be happier than you were before, even if it made a permanent, beneficial impact on you. Similarly, something terrible happens? Sorry, but know that you'll probably be roughly as happy as you were before in a relatively short period of time. In a 1978 study, two academics interviewed groups of lottery winners and accident victims, people whose quality of life had been clearly improved or worsened, respectively, and found that both groups were roughly as happy after the life-altering event as they were before.

To me, at least, this makes intuitive sense and is something I can recognize in myself, but it was the application to baseball that really caught my mind. A player breaking out or collapsing is thrilling and something that we can't help but pay attention to, but when Mike Trout is continuing to be Mike Trout, we've adjusted. He's not the only one either; how much have you heard about Kris Bryant lately? As far as I can tell, we've run one article on him here at BtBS, about his home/road split, from April 20th, and neither FanGraphs nor Baseball Prospectus has run an article about him at all this season. Through 266 PAs, he's improved by about 1 fWAR/600 and 1.3 WARP on his already-excellent 2015, but all it took was a season of him being very good for us to be able to ignore it. The treadmill has brought us back to center.

This isn't a call to action or anything like that. Should we appreciate Trout and other consistently great players more? Maybe, but I am generally a proponent of everyone enjoying baseball however they see fit, and trying to change your genetic hard-wiring seems like a bad way to do that. Instead, with the hedonic treadmill in mind, what I want to do is find the best careers of all time. Not "best" in the sense of "most career WAR" or whatever—we already know who those players are—but "best" in the sense of "created the most happiness, despite humanity's tendency to ignore anything that isn't new."

I took every position player season from 1900 on and looked for seasons where a player noticeably improved upon his previous season. "Noticeably" is a fuzzy term, so I picked a jump of 1.5 fWAR/600, which seems like the kind of leap forward that would get talked about. This assumes a couple things, with the most debatable one probably being that when a player goes from very good to bad then returns to very good, it's not treated as a return to normal but a jump. Victor Martinez is a good example of this kind of thing, and when I think about the reactions I've seen to his current good-but-not-great-but-way-better-than-last-year performance in 2016, I am comfortable including it as a treadmill-beating season.

Now, I know I said this wasn't going to be the players with the most career WAR, but the top of this list overlaps a lot with the top of that one. That makes a lot of sense; a player has to be very good to keep improving and keep us marveling at his career year after year. There are 19 players tied with seven seasons of marked improvement, including Rogers Hornsby, Ted Williams, Mickey Mantle, Alex Rodriguez, George Brett, Carlos Beltran, and Andres Galarraga, to name a few.

A leaderboard with a 19-way tie for first wouldn't be an exciting leaderboard. Luckily, that's not this one. Above those 19 players with seven seasons of marked improvement, there's one player with 11. The gap between first and second is as large as the gap between second and 389th. If this seems astonishing, it should. Who could do this? What one player could so thoroughly destroy the rest of baseball? Who had a long enough career, with enough amazing seasons, to constantly amaze us and somehow overcome our own tendency toward disinterest?

Steve Mitchell, USA Today

Who else?

Bonds was hyped his entire career, and over that time he constantly managed to build upon and exceed that hype. When he debuted in 1986 with the Pirates, he immediately established himself as a regular, contributing positively on both sides of the ball and earning 3.3 WAR in 484 PAs (attention-grabbing season number 1).

He made another leap in his sophomore season, and though he still didn't look like the Barry Bonds we now know, he improved on both his offense and defense and saw his WAR rise to 5.3 (2). He had his first truly great season two years later, in 1989, and though his offense actually declined from the previous year, his excellent defense pushed his WAR total up to 7.1 (3).

But 1990 was his first incredible season, with his defense regressing slightly from the year before and his offense exploding. A 165 wRC+ was his highest of his career, and his 9.9 WAR was as well (4). Through his first five seasons, Bonds had already hit four distinct tiers of excellence and blew away the expectations of those watching each time.

1990 was only the beginning, however. He fell to a lowly 7.8 WAR in 1991 then tore the cover off the ball for all of 1992, with a 198 wRC+ and 9.6 WAR (5) despite contributing essentially nothing on defense at this point. His first year in San Francisco, 1993, was the best of his career, but at 10.5 WAR probably not enough better than the previous season to really catch the attention of people watching.

A strike-shortened 1994 yielded only 6.0 WAR, but that meant that 1995's 7.7 WAR (6) and 1996's 9.2 WAR (7) both were eye-catching improvements, putting any notion of a decline to bed. After two more outstanding seasons, 1999 again saw Bonds' season get cut short by injuries, which likely sapped some of his hitting as well. A 3.3 WAR age-35 season would likely be the beginning of the end for many, but Bonds was the best hitter ever (and also had access to performance-enhancing drugs), so he came roaring back in 2000 with 7.6 WAR (8).

That season, as good as it was, was only the lead-in to the greatest four-year stretch of all time. In 2001, Bonds had a 235 wRC+ and accumulated 12.5 WAR (9), a total he would beat in the next season. His 2002 is exactly the sort of season the hedonic treadmill specializes at making us barely notice at the time that it's happening. I was only a kid, so I don't remember this, but I wonder what the conversation around Bonds was like at the time. He was having one of the best seasons ever, full stop, but it was nearly the same as what he had done just last year. Like Trout, my guess is people were more interested in new things, like Alfonso Soriano's 5.6 WAR breakout. In 2003, Bonds looked to be returning to the realm of mortals, with 10.2 WAR, but he once again defied gravity in 2004, rebounding to 11.9 WAR (10).

He played only 14 games in 2005, and yet again it seemed like Bonds' career was at its close. 2006, however, saw him make one last resurgence, with a 146 wRC+ in 493 PAs in left field, good for a 3.2 WAR (11). When it's laid out like that, it's easy to see why he made the top of this list by so much. Lots of players reach their peaks quickly or increase incrementally. Due to Bonds' own incredible talent and the chemical enhancement he benefitted from, however, every time his career seemed to be declining, he reset his trajectory and captured everyone's attention yet again.

Again, the hedonic treadmill seems like a bad thing, both in baseball and otherwise, but trying to change it seems foolish. Luckily for us, we had Barry Bonds to keep us from becoming complacent, and he blew the league away at every possible opportunity.

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Henry Druschel is a Contributing Editor at Beyond the Box Score. You can follow him on Twitter at @henrydruschel.