English football has featured successful Americans before Christian Pulisic joined Chelsea. Tim Howard put in more than a decade of top-class work as Everton's goalkeeper after a spell at Manchester United, and Brad Friedel logged 450 league appearances in the net for Liverpool, Blackburn Rovers, Aston Villa and Tottenham Hotspur.

Further up the pitch, Clint Dempsey scored 72 goals for Fulham and Tottenham, while Brian McBride could have done something similar with the same opportunities; he scored 41 times in England despite not playing his first full season there until age 32. Carlos Bocanegra was a rock at the back for Fulham for five seasons, and Claudio Reyna made over 100 appearances for Sunderland and Manchester City.

At 21, however, McBride and Friedel had not yet made their professional debut, Dempsey and Bocanegra were just getting started in the MLS, and Howard was a backup for the New York/New Jersey MetroStars. Reyna and USMNT joint-top scorer Landon Donovan had both signed with Bayer Leverkusen by that age, but Reyna was prepping for his debut, and Donovan was on loan in America.

Simply put, there is no American comparison to what Pulisic is accomplishing in the world's most lucrative soccer league. We have to spread the net wider.

- ESPN Daily podcast: Pulisic's is the U.S.'s first global star
- Pulisic Watch: Tracking his debut season in England
- Karlsen: Pulisic among the world's best Under-21s
- ESPN+: Stream Pulisic in FA Cup semis (July 19) | FC Daily

Whittling down the field

Let's create a specific type of attacker from a player pool consisting of everyone in Europe's big five leagues. He needs to have played at least 1,000 minutes this season, averaged at least 55 touches per 90 minutes, attempted 35 passes and taken seven touches in the opponent's penalty area.

By that criteria alone, we are down to just 14 players. They are diverse talents, guys heavily involved in both ball distribution and direct attack; players such as Barcelona's Lionel Messi, PSG's Neymar and Kylian Mbappe, Man City's Raheem Sterling and Riyad Mahrez.

Now let's take this a bit further and make our player a solid passer (completion rate of at least 80%) with a better-than-average nose for the goal (at least 0.4 goals per 90). Let's also make sure he is involved in team defense by averaging at least 3.7 ball recoveries per 90.

Now we're down to five: Neymar, Atalanta's late-blooming star Josip Ilicic and three of the best wingers in the Premier League: Mahrez, Liverpool's Sadio Mane -- four players at least 28 years of age, who are at or just past their athletic primes -- and Pulisic, a 21-year old American in his first Premier League campaign.

This set of specifications, while conveniently specific, hones in on a certain type of star. David Silva pulled off this combination for pre-Pep Guardiola Man City in 2014-15; Franck Ribery did so for Bayern Munich twice; and Sterling and Leroy Sane have achieved in recent years for Guardiola at Man City. Ribery and Silva were far more involved in ball pressure than Pulisic, and Neymar certainly scores more goals. But none played at this level at Pulisic's age.

Pulisic has had to adapt at Chelsea

Pulisic arrived at Stamford Bridge from Borussia Dortmund last summer, a January signing who stayed in Germany for the rest of the season to help with BVB's Bundesliga title chase. (They came up two points short.) He had made his BVB debut at age 17 in the 2015-16 season and became a mainstay in the team the next year, primarily on the right wing. Let's take a closer look:

His first two full seasons were pretty up-and-down, as you might expect for a teenager. He was used in advanced positions in 2016-17, attempting riskier passes but getting a lot of touches in the box; in 2017-18, he sat further back, improving his completion rate but seeing fewer goal and assist opportunities.

In 2018-19, Pulisic blossomed for a dramatically improved BVB despite a series of muscle injuries and increased competition from players such as Jadon Sancho. After playing at least 1,500 league minutes in the two previous seasons, Pulisic logged only 923, but in those he thrived.

By the end of his time in Germany, Pulisic had combined the attacking numbers from his first full season with the ball-advancement numbers of his second. During that season in the Bundesliga, only four players averaged at least 0.35 goals per 90 and 0.35 assists over 900+ minutes: Sancho, Pulisic, BVB's Mario Gotze and Eintracht Frankfurt's Sebastien Haller, who moved to West Ham United for £45 million last summer.

Life in the Premier League is grueling. There are four more matches than in the Bundesliga and teams do not get a month-long winter break. Pulisic again had to fight for playing time on a roster loaded with young talent, and it took him a while to carve out a niche. Plus, he dealt with another round of muscle injuries; he had yet to play in 2020 before the coronavirus pandemic stoppage.

On top of that, he was asked to cover a lot more ground for Chelsea, and on the opposite side of the pitch. His touches heat map for 2019-20:

"The beginning, it wasn't always easy," Pulisic told ESPN's Jeff Carlisle in January, "and I wasn't always in the lineup, but I just kept working. I put my head down, and I just kept telling myself, 'My time will come.'"

And it did. Once he began finding steady rotation time, Pulisic began to produce.

Carlisle and other ESPN writers have been rating Pulisic's performances on a scale of 1 to 10 (first half of the season and second half). After averaging 5.7 in August and September, he tallied 7.0 in October and November, then slid back to 5.8 in December. Heading into Tuesday's match against Norwich City, he had averaged a 7.5 since the league restarted last month.

Pulisic has been an integral piece of Chelsea's attack. His assist numbers are down from his final season with BVB, but he is averaging more touches in the box and, consequently, more goals. Combine that with a higher pass completion rate and, injuries aside, you've got a solid and unique debut campaign.

Projected over 38 games, that's a 17-goal, 6-assist pace. Including his BVB goals, he'll top Dempsey's European total within a couple of years.

Who are Pulisic's peers?

Granted, he hasn't yet proved himself incredibly durable; there's nothing saying he's not, but the sample size needs to grow quite a bit before we know one way or the other. Still, it's clear Pulisic has made the transition from "incomparable to any past American prospect" to "incomparable to any past American pro" pretty easily. So if we're tracking both his potential and his progress, we've got to raise the bar for the comparison group.

Let's go back to the two other elite wingers in the whittling exercise above: Mahrez and Mane. Pulisic's rate stats aren't quite as good this season, though they're pretty comparable to Mane.

Again, though, Mahrez is 29, and Mane is 28. They are finished products or close to it. So what if we compared like for like and looked at recent elite wingers in either their Premier League debut seasons or, in the case of Sterling, their age-21 campaign?

This is an incredibly aspirational group, and Pulisic's stats don't quite match up. Still, he is a steadier (or perhaps safer) passer than some, while his recent run of goals has made him the most successful scorer in the bunch. Plus, his offensive stats are superior to Sterling and they continue to be awfully similar to those of Mane, even though Mane was older (22) when he moved from Red Bull Salzburg to Southampton. That comparison will never not be friendly to Pulisic.

How can Pulisic get even better?

There are two clear opportunities for growth moving forward. Pulisic's assist averages, though pretty close to most on the list, are far behind those of Philippe Coutinho and Eden Hazard. Pulisic is more of a receiver than a passer -- despite his assist for Olivier Giroud against Norwich -- but a lot of the players on this list grew to become both.

Even more noticeable, however, is the last column: ball recoveries. These are basically loose-ball collections, and they are pretty good hints of both how close a player is to the ball and how involved he is in defensive pressure.

Each of the six non-Pulisic wingers above averaged at least 4.7 recoveries per 90 -- at 6.9, Mahrez was a dang wrecking ball out of the gates with Leicester City -- and the highest average Pulisic has enjoyed to date is 4.0, two years ago at Dortmund.

We know his anticipation and acceleration skills are lovely, as evidenced by his one-man breakaway goal against Man City last month. But either he hasn't been asked to get involved that much in the pressure game or he just hasn't quite been at the same standard as elite players.

Still, Pulisic holds up reasonably well in comparison to some of the best wingers and, with Chelsea adding some incredible attacking pieces for next season -- RB Leipzig's Timo Werner, Ajax's Hakim Ziyech have already been signed -- he will have chances to improve those goal and assist numbers. With midfield and defense lacking in comparison with attack, Chelsea could probably use every ball recovery he can manage, as well.

Both the present and the future are brighter for Pulisic than for any previous American player.