Just as we were all finally getting over our Kris Bryant Day hangovers, the Cubs gave us something else to celebrate. As you’ve likely heard by now, the Cubs summoned Addison Russell to the major leagues yesterday. He started at second base last night, and went 0-5 in his big league debut.

Russell’s promotion came as something of a surprise. Although he’s a very talented player, and is one of the most highly-regarded prospects in the game, he’s had very little exposure to high-minors pitching. He’s played all of 77 games above A-Ball, and only 14 of those games came in Triple-A. Due to this relative lack experience, most anticipated that Russell wouldn’t make it to the majors until late 2015, if not sometime 2016. Yet here we are. It’s April 22nd and Russell is playing major league baseball.

Although he’s still just 21, Russell’s been gracing the tops of prospect lists for a few years now. He was drafted by the A’s with the 11th overall pick in 2012, and wasted no time making a name for himself with his minor league performance. He hit .354/.416/.568 across three levels in his draft year, closing out the season as an 18-year-old in the full-season Midwest League.

He moved on to High-A in 2013, and kept right on hitting. At 19, he was very young for the California League, but still managed a .275/.377/.508 performance. Not many prospects are assigned to High-A as teenagers, and even fewer hit as well Russell did at his age. It comes as no surprise that Russell’s 2013 campaign earned him a KATOH projection of 9.0 WAR through age-28, which would have been the 13th highest rating of any prospect this year.

Russell advanced to Double-A in 2014, but sat out most of the season’s first half while rehabbing a hamstring strain. He returned to action in June, and was promptly dealt to the Cubs in the Jeff Samardzija deal. Around the injury and the trade, Russell got into 68 games — all but five of them in Double-A — and batted .295/.350/.508. Just as he did in the lower levels, he managed to be one of the better hitters in his league thanks to a decent batting average and oodles of power. This time around, KATOH pegged him for 13.1 WAR through age-28 — good for 4th bast among prospects.

Russell’s 2014 campaign was a solid one, but there was one area of his game that didn’t carry over into Double-A: His walk rate. After walking 12% of the time in 2013, Russell walked less than 7% of the time last year. Russell’s walk rate has followed a curious trend in his two and a half years as a pro. He walked pretty infrequently as an 18-year-old who was fresh out of high school. Then he walked a bunch as a 19-year-old in High-A, especially late in the year. But since he opened the 2014 season in Double-A, his walks have been disappearing.

A confluence of factors go into a hitter’s walk rate, which makes it tough to explain this trajectory, especially since it came against a wide array of competition levels. Plus, since we’re looking at one-month samples, random variation surely played some role. But regardless of what the long-term trend looks like, the bottom line is that Russell hasn’t drawn very many walks in the recent past. And he’s barely walked at all in the very recent past.

Since he joined the Cubs organization last July, Russell has drawn a walk in just under 4% of his trips to the plate. Even in a small sample of games, such a low walk rate should raise some eyebrows, especially coming from a player who hits for as much power as Russell does. These sparse walks might be a sign that he’s apt to chase pitches outside of the strike zone. And as we saw with Javier Baez last year, this is a flaw that can be a real problem if it’s exploited by big league pitching.

To try and zero in on players with Russell’s unique combination of low-walk high-power skill set, let’s pull up some comps. Below, you’ll find a list of all hitters aged 19-21 whose league-adjusted walk rate, strikeout rate, BABIP, ISO and stolen base frequency fell within 1.25 standard deviations of Russell’s marks from Double-A. The table includes each of these hitters’ major league stats through age 28.

*Note that the jury is still very much out on what will become of 23-year-old Randal Grichuk.

There are a few guys at the bottom of this list whose plate discipline prevented them from ever blossoming into usable players. Any list of comps that includes Ruben Mateo is somewhat concerning, but overall, we see some very good players in this group. A trajectory resembling Jose Vidro‘s or Tony Batista’s would surely be a welcomed development for the Cubs.

Given his statistical track record, Russell looks like a good bet to be a productive big leaguer over the next several years. In fact, he’s a better bet to do so than almost any other hitter in the minors. Very few prospects can match what Russell’s accomplished through age-20, and of those who have in the past, many have gone on to do very good things in the big leagues.

Nonetheless, while his long-term upside looks rosy, today’s version of Addison Russell appears to be a little rough around the edges. Although he’s done nothing but hit in the minor leagues, his plate discipline seems a little suspect, and it remains to be seen if big league pitching will be able to further exploit this weakness. Additionally, since he just arrived in Triple-A two weeks ago, nearly all of his minor league success has come against pitchers in Double-A or below. The jump from Triple-A to the big leagues is tough enough as it is, and the gap from Double-A to the majors is even wider. Taking all of this into account, Steamer forecasts Russell for a meager 86 wRC+ this year.

As Dave Cameron pointed out yesterday, Russell’s promotion might have more to do with the Cubs position on the win curve than with Russell’s development. For the first time since 2008, the Cubs seem to have a legitimate shot at playing October baseball. Even if he endures some rough patches, Russell very well might be able to provide them with the extra win or two they’ll need to secure a playoff berth.

Still, this isn’t to say Russell definitely won’t step in and be an All-Star caliber player right away. Russell may not seem quite ready for the show based on his 2014 numbers, but I would have said the same thing about Manny Machado in 2012, Starlin Castro in 2010 or Hanley Ramirez in 2006. Yet despite their lack of minor league track records, this trio transitioned to the big leagues seamlessly. Sometimes a top prospect’s tools coalesce into on-field performance right when he’s arriving to the majors, which enables him to blow past his single-season projections.

Regardless of how Russell fares in his first taste of the big leagues, he seems to have a bright future ahead of him. Hitters who put up ISOs north of .200 without striking out all that often don’t grow on trees, and coming from a shortstop — or even a second baseman — this type of performance is all sorts of impressive. Russell may or may not be an impact player in 2015, but the tools are certainly there, and it should be fun to watch him use those tools as he attempts to rise to the challenge of facing big league pitching.