Nolan Arenado to the Cardinals - Fantasy Impact

Well. It finally happened. The day Rockies fans had long dreaded. News broke late Friday night that Colorado had traded their franchise third baseman Nolan Arenado to the St. Louis Cardinals.

The five-time All-Star has been the biggest star in the Mile-High City for some time now, as he is in the top-10 career leaderboard for just about every offensive category — including ranking fourth in WAR among position players, trailing only Troy Tulowitzki, Larry Walker and Todd Helton. The Cardinals will be sending a package of mostly prospects out west in this trade although the deal is not officially in the books yet. It appears that it may include left-handed reliever Austin Gomber, pitchers Jake Woodford and Angel Rondon, first baseman Luken Baker, and outfielder Jhon Torres headed to Colorado.

When the details are confirmed on who is heading to the Rockies we'll write a follow-up on their fantasy impact, but for now we'll focus on Arenado's value in St. Louis and how the void he leaves in Denver will be filled.

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Domo Arenado, Mr. Cardinal

Arenado has been a monster on offense since 2015, averaging (averaging!) 40 home runs and 124 RBI with a .300/.362/.575 slash line from 2015 through 2019. 2020 was a down year for him though as he slashed .253/.303/.434 over 48 games — his worst numbers since his rookie campaign in 2013. However there is an explanation for that as Arenado played through a shoulder injury he suffered five games into the season, and he would eventually end up on the injured list for only the second time in his career.

The numbers bear evidence that the injury affected him, as Arenado posted a career-best 19.1 degree launch angle but he just couldn't generate much power with an 87.8 mph exit velocity and 33.7 percent hard-hit rate — both of which were career-worsts. And even while injured Arenado showed improvement in his plate discipline, posting a 10 percent strikeout rate and  7.5 percent swinging strike rate — both career-highs — while also recording his second-highest contact rate at 84.2 percent.

So it seems like we can more or less write off 2020 as a fluke season due to the shoulder injury. But there's a bigger issue to address: the dreaded Coors Field home/road splits. Check out his career home/road splits below, as well as his stats over 24 games playing in Busch Stadium:

And then to get a little better picture let's also compare his batting average and slugging percentage with his expected average and slugging percentage since 2015:

Clearly, Arenado has benefited from playing at Coors Field over his career. His batting average likely won't take much of a hit with the move to St. Louis, as he has on average hit only about 27 points higher than his expected batting average. But the power could see a more noticeable dip, as Arenado has on average seen his actual slugging percentage almost 75 points higher than his expected slugging percentage. But that all doesn't necessarily mean he'll flop in St. Louis.

For starters, in 2019 Arenado did show some improvement away from Coors Field as he posted a slash line of .277/.346/.521 across 78 road games. And then on top of that, his career numbers at Busch Stadium are among the best he's put up at any road stadium. His .511 slugging percentage at St. Louis, in particular, is the highest he's recorded at any road stadium that he's played at least 20 games at.

2021 Outlook

Taking a quick look at the situation in Colorado now, there could be a fair amount of shuffling around in the infield. Ian Desmond will return in 2021 after sitting out last year, and he could take over at first again with the retirement of Daniel Murphy. Josh Fuentes was projected by Fangraphs RosterResource as the starter at first, but now he could slide over to his natural position at third with the departure of his cousin. If that doesn't happen, there could be some competition with Ryan McMahon, Brendan Rodgers, and Garrett Hampson for playing time between second and third.

Regardless of who takes over the hot corner in Colorado, none of the Rockies options will likely be fantasy-relevant in most leagues — at least to start the season. Currently, the highest-drafted guy out of this bunch is McMahon with an ADP of 254 followed by Hampson at 271.

Getting back to the star of this deal, the bottom line is Arenado's numbers will almost certainly take a dive this year playing outside of Coors Field, but he's still going to be a top-10 third baseman in fantasy without question. A reasonable projection for Arenado would be an average around .280 with about 30 homers and a slugging percentage right around .500. RBIs are much harder to predict of course since it's very much dependent on how the other batters in the lineup perform, but when you take into account the projected dip in average and add in the fact the last Cardinal to have 100 RBI in a season was Matt Holliday with 102 in 2012, the cards appear stacked against Arenado reaching his 2015-19 average of 124.

If you want a comparison for what to expect from Arenado, Anthony Rendon appears to be a good fit. Rendon slashed .286/.418/.497 in 2020 and with nine home runs over 52 games he was on pace for a 29-homer performance over a full season. Arenado is currently the fourth third baseman coming off the board in drafts with an ADP of 33 while Rendon is number six with an ADP of 42. Anywhere in that 33 to 42 range is a good place to target Arenado, as he will still be a productive fantasy player despite leaving Colorado. And if he somehow drops to 45 managers should not hesitate to grab him then.

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