Sometimes it’s hard to come up with a writing prompt. Other times, Adrian Heath trolls away in press conferences and practically begs me to spend hours scouring data.

This past week’s clean sheet streak has been a welcome delight for Loons fans. It’s also come with a big dose of hubris, with Heath repeating his refrain on Sunday from the post-game comments against the Galaxy on Wednesday:

“Another clean sheet which will please all you lot and stop you writing about it again this week. So that’s good. I don’t have to listen to it again all week.”

Give credit where it’s due: this has been a good week defensively for Minnesota United. It’s the first time in the team’s MLS history that they’ve held teams scoreless in consecutive games, and per data from American Soccer Analysis it’s also the third time since 2017 that they’ve allowed fewer than one xGP (expected goal by placement) conceded per game for a two-game rolling average. Last Wednesday’s game against the Galaxy was the team’s second-best xGPA in their MLS history. Against DC United they marked their sixth-best. Each came against strikers who recently starred for Manchester United. Progress!

However, the two elephants in the room loom large. First, how much of this can we simply ascribe to not playing Francisco Calvo? Second, how sustainable is Minnesota’s newfound defensive strength?

To hit at the first question, I pulled match data from each of Minnesota’s MLS games in 2018 and 2019 from WhoScored to see how many goals, shots, shots on target, and key passes the team allowed, specifically coding for those that came from the field segment covered in the formation by Francisco Calvo. If slotted in at left center back, I counted shots taken from within the 18-yard box to a line corresponding with the penalty spot, while counting all key passes within those horizontals to the top of Minnesota’s defensive third; as a left back or left wing back, I counted all shots and key passes in a box corresponding with the touch/end lines, the top of the defensive third, and the left side of the 6-yard box. I also did the same for his most recent common position for games where he was out of the starting lineup, signified by “Out.” I also tracked WhoScored’s right-side attack zone percentage for the opposition for each game—the side that would be attacking Calvo on the left—and American Soccer Analysis’s xGPA per game.

Figure 1 - Calvo By Year at Left Back Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG 2019 LB 7 15.29 6.57 2.43 0.57 15.89% 8.70% 11.86 3.57 30.12% 39.29% 2.14 1.80 2018 LB 6 13.67 5.17 1.33 0.67 9.76% 12.90% 10.17 3.00 29.51% 34.00% 2.50 1.55

The results aren’t pretty this year. Comparing Calvo’s seven games at left back this season to his six in 2018 finds Minnesota conceding 1.6 more shots per game, with 1.4 more going on target. The Loons are also conceding 1.7 more key passes per game. It may not surprise you to hear that Calvo is being targeted with greater frequency as well, suffering 1.1 more shots in his segment of the field than last year and 0.6 more key passes. Calvo’s flank last season was one that teams played with relative balance—34% of attacks in those six games went down his side of the field. In the seven this year, however, teams have zeroed in on the left, attacking it 39.3% of the time. While the result has seen fewer goals scored (2.5 in 2018 versus 2.14 in 2019), teams are averaging a quarter of a goal more in xGP—this is with the addition of Ozzie Alonso, Ike Opara, and Romain Metanire in the rear block.

Figure 2 - Calvo’s 2019 Versus His 2018 at Center Back Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG 2019 LB 7 15.29 6.57 2.43 0.57 15.89% 8.70% 11.86 3.57 30.12% 39.29% 2.14 1.80 2018 LCB 20 16.20 5.85 5.10 2.05 31.48% 35.04% 12.35 2.95 23.89% 38.25% 1.80 1.67

Many of the defensive numbers with Calvo playing left back in 2019 have actually regressed to levels that caused the pitchforks to come out last year when he played at center back. Minnesota allowed 16.2 shots per game and 5.85 on target in the 20 games when Calvo played as a center back last season, with 5.1 shots (31.5%) coming in Calvo’s segment of the field and 2.05 (35%) of those hitting the target. So far this year, while Minnesota has allowed fewer shots with Calvo as a left back (15.3 per game), the team has actually allowed 6.6 of those to hit the target. While the team has allowed fewer key passes per game than in Calvo’s time in the center (11.9 versus 12.35 last year), Calvo’s segment out wide has taken on a 6.2% higher proportion of the key passes, as well as seeing a 1% higher proportion of opposition attack targets to Minnesota’s left.

Figure 3 - Calvo In and Out of the Lineup Since 2018 Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG 2018 Out 8 18.13 7.63 4.63 2.25 25.52% 29.51% 13.25 4.00 30.19% 34.38% 2.50 2.26 Total Out 10 16.80 6.60 4.00 1.90 23.81% 28.79% 11.80 3.30 27.97% 34.50% 2.00 1.92 Total In 33 15.55 5.88 3.85 1.48 24.76% 25.26% 11.85 3.09 26.09% 37.70% 2.00 1.68

The overall numbers between Francisco Calvo being in the lineup and being out of it are starting to approach parity. Since 2018, Calvo has missed 10 games; in those games, the team has allowed 1.25 more shots and 0.72 more shots on target, with the area he vacated roughly level on shots taken (4.0 out, 3.85 in) and behind on on-target shots taken (1.90 versus 1.49). However, the team now averages exactly two goals allowed regardless of if he’s in or not, and his being out of the lineup spreads the opposition’s focus away from the left of the field by 3.2%. What’s more, the numbers with Calvo out include the team’s dismal eight games where he was absent in 2018—allowing the most goals, xGP, shots, shots on target, and key passes of any segment.

Figure 4 - Calvo In and Out in 2019 Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG Segment Games Shots Against MNUFC PG Shots On Target Against MNUFC PG Shots In Calvo's Area PG Shots On Target in Calvo's Area PG Proportion of Shots in Calvo's Area Proportion of Shots on Target in Calvo's Area Key Passes PG Key Passes In Calvo's Area PG Proportion of Key Passes in Calvo's Area Percentage of Attack Against Left Flank PG Goals Allowed PG Expected Goals (Placement) PG 2019 LB 7 15.29 6.57 2.43 0.57 15.89% 8.70% 11.86 3.57 30.12% 39.29% 2.14 1.80 2019 Out 2 11.50 2.50 1.50 0.50 13.04% 20.00% 6.00 0.50 8.33% 35.00% 0.00 0.55

I must warn you: SMALL SAMPLE SIZE. This past week has seen Minnesota play against the second-highest scoring offense in the East and the fifth-highest in the West and record the best by-segment numbers the team has had in the last two seasons in shots and shots on target allowed, key passes allowed, xGP, and (obviously) goals allowed. The Loons beat this year’s prior overall shots allowed by 3.7 per game, shots on target by 4.0 per game, and key passes by 5.9 per game. Eric Miller allowed 0.9 fewer shots and 3.1 fewer key passes in his field segment in those two games than Calvo did out on the left despite getting targeted by a Manchester City youth product in Uriel Antuna and a Paris-St. Germain target in Luciano Acosta—all in his first minutes, competitive or otherwise, this season. Both sides recognized this, attacking the left of Minnesota’s defense 4.3% less than with Calvo on the field.

When lumping in Calvo’s 2018 performances, things are even as to whether or not his presence hurts the lineup. But when comparing current performance levels to last year, he’s been as much of a hindrance to performance as he was as a center back in 2018. The small sample numbers echo the eye test that the Loons are a better defensive team without El Capitan in the lineup.

That said, the second question is a little bit more subjective. If we trust the data that Calvo’s detriment to the lineup has made opposing teams more apt to attack his segments of the field, the easy answer for how long to trust Adrian Heath’s confidence in a shutout streak of 200-odd minutes is the same as Heath’s plans to trust people not named Francisco Calvo to man the back line. If he keeps things at status quo, things should continue to pan out, right?

That involves having to trust Eric Miller to continue to maintain the same level against additional opponents. Miller hasn’t played more than three consecutive games since a stretch for Colorado ending in September of 2017 and has had just two streaks of starting consecutive games as a left back in his six year career. Saturday’s match against Seattle could be worse for the Woodbury native: the overlapping right back Kelvin Leerdam will be suspended for a red card against LAFC last weekend, while Jordan Morris will likely play the #9 with Raul Ruidiaz’s continued heel injury. However, it’s hard to imagine Adrian Heath putting as much faith into Miller as he has to Calvo.

There’s also the more systemic shifts that have come from the last couple games. Minnesota played a more conventional six-man defensive block against the Galaxy as a result of Jan Gregus’s red card suspension, pitting Rasmus Schuller as a dual defensive midfielder with Ozzie Alonso rather than the despised two-way “double pivot” he worked with Ibson in 2018. When Gregus returned, Adrian Heath opted to keep Schuller in the middle and work out of a 4-3-3 with Darwin Quintero shifted wide, effectively making a seven-man defensive block with Romain Metanire keeping the right to overlap offensively. That solidified the team’s defensive shape to absorb pressure from two high possession teams, but it came at the expense of offense: Minnesota’s xGP was its lowest of the season against DC United (1.00), and its third-lowest against the Galaxy (1.28).

The potential injury to Darwin Quintero could put a wrench into things and force a continued 4-3-3 with a true wide player out on the left. That might not be a bad thing considering the chances generated in the second half against DC—check this graph of expected goal differential by minute made by American Soccer Analysis, and keep in mind when Quintero went out injured:

Miguel Ibarra was a clear lift, but if that’s not enough to clear the issues scoring goals it certainly stands to reason that Heath will look to sacrifice some of the defensive shape that he’s gained with this current back four and midfield. Therein lies the value of Francisco Calvo, whose five goals and three assists (7.6 xG+xA) in 5,768 career MLS minutes thrash those of Eric Miller—one assist and 4.1 xG+xA in 7006 minutes since 2015. The value of Miller has precisely been that he is a defensive specialist in the wake of Calvo, but lest the two clean sheets obscure the 156 goals allowed in 77 games since 2017, Adrian Heath is not a defensive specialist, and should Miller’s value defensively wane from a stellar two games on the bounce, who knows what sort of move Heath will make.

That’s why we still write about the defense.