Last season Liverpool, a storied soccer club that hasn’t won England’s top division since 1990, was in the race for the title down to the final day. Having finished seventh the previous campaign, everything was finally going right – but did the referees have anything to do with it?

Liverpool certainly had plenty of English fans, regardless of their favorite team, rooting for them to unseat the league’s recent powerhouses. Their dogged captain, Steven Gerrard, supplied a fiery passion to the team, and the effervescent talents of Raheem Sterling, Daniel Sturridge, and Luis Suárez provided the goals. As Liverpool’s mainly homegrown squad duked it out with Manchester City and Chelsea, two clubs stocked with foreigners and funded by petroleum billionaires, it sometimes seemed that the Reds were on a divine mission from an English god.

Along the way, Liverpool racked up an enormous number of spot kicks when its players were fouled in the opposing penalty box. The club’s 12 penalties were more than any other Premier League team’s haul in the past four seasons, with only Manchester United in 2011-12 and Chelsea in 2012-13 mustering 11. Without the goals scored from these spot kicks, Liverpool might have had six fewer points at the end of the 2013-14 season. By contrast, Liverpool’s opponents only received four penalty kicks.

The Reds also had a huge advantage in cards. A player shown two yellow cards or one red must leave the field—a costly loss for his team—and miss the next match as well. Referees showed yellow or red to Liverpool’s opponents 94 times, also the most for any team in recent years. But Liverpool’s own players saw only 55 cards, the 67th highest total out of the 80 from the past four seasons of the 20-team league.

One possible explanation for these data is that Liverpool’s attackers were unplayable, and teams were forced to resort to cynical fouling, even inside their own penalty boxes. A few commentators also suggested that Liverpool’s players, especially Sterling and Suárez, fooled referees into thinking they had been fouled; each won three penalty kicks out of Liverpool’s 12. Though the two strikers are undeniably tricky to mark, there’s also a third possibility: Referees gave Liverpool some help.

It’s well known in soccer that referees can be swayed by home crowds. On average, home teams received 2.8 penalty kicks per season versus 1.9 for away teams in my sample. If Liverpool got a few extra calls at home, it might be hard to distinguish the effects from the usual home-field advantage in officiating. But if the Reds were also favored on the road, that would indeed be striking.

Nine of Liverpool’s 12 penalty kicks came on the road. The runner-up in this category was Wigan Athletic, in 2011-12, with six. To find out whether the nine calls were more or less justified, I could have just sought out the videotape of each incident and judged for myself. Every angle can tell a different story, though, and it’s hard to experience the plays exactly as the referees did. Instead, I decided to focus on cards, which were much more frequent.

Cards in soccer are given for misconduct and time-wasting, but more often for fouls that the referee considers dangerous or repetitive. Not surprisingly, there’s a strong correlation between the fouls a team suffers during a season and the number of cards its opponents receive, both at home and away. Still, there is a home-field advantage.

Over the four seasons in my sample, teams playing on the road were fouled 7.5 times on average for each card their opponents received, versus just 6.1 fouls per card at home. For Liverpool in 2013-14, these figures were both much lower, and their order was flipped as well: 4.2 fouls per card away, and 5.1 fouls per card at home. In other words, referees were especially harsh on Liverpool’s opponents, and even moreso when the Reds were outside the friendly confines of Anfield Road.

This result persisted even when I adjusted for other factors that might have been associated with opponents picking up cards, such as dribbling and being tackled. No matter how I sliced the data, Liverpool was always a big outlier. But before I concluded that the referees were biased, I wanted to check one thing: Did the apparent favoritism grow as the title race neared its end?

With half the season gone, the Reds were only in fifth place, six points behind the leaders, Arsenal. But on March 1, the club vaulted into second with a 3-0 away win at Southampton. Throughout their remaining 10 matches, they were contenders. Now compare two graphs of predicted cards versus actual cards during the two periods. Here are the first 28 matches:

And here are the last 10 matches:

(That other big outlier is Arsenal in 2011-12. The club’s advantage in cards wasn’t reflected in penalty kicks, however, with just three awarded during the whole season. A more complex study actually suggested Arsenal benefited least from positive bias among referees in 2011-12 when it came to penalties.)

Through Liverpool’s first 28 games of the 2013-14 season, the team’s opponents did receive a rather high number of cards, if not extraordinarily so. Yet in the last 10 games, which also featured five of Liverpool’s 12 penalty kicks, the difference was startling. Even in a hostile environment where enemy fans held sway, some referees gave Liverpool the edge. They were just like so many of their compatriots—they wanted a title for the Reds.