Defenders have an unfair route to extra points
Gameweek 6 proved defenders are twice as likely to hit defensive thresholds as midfielders.
Defenders get two extra points for ten clearances, blocks, interceptions, and tackles. Midfielders and forwards need twelve. It sounds like a slight difference, but in gameweek 6 it turned into a massive divide.
Gameweek 6 data. Defenders needed 10 actions while others needed 12.
24 of 107 defenders who played in gameweek 6 secured the bonus points. That is more than one in four. For midfielders and forwards, only 17 of 188 reached twelve actions. You were almost three times more likely to get defensive baseline points from a defender than a midfielder.
When you buy a budget defender, you are no longer relying solely on a clean sheet. A full 90 minutes in a busy match is often enough on its own.
Gameweek 6 match stats. Highlighted player costs 4.0m.
Thomas topped the chart in gameweek 6 with 22 defensive actions for Coventry. He got four points despite conceding goals and keeping no clean sheet, entirely because his work rate triggered the bonus. His team-mate 
van Ewijk managed 14 actions and banked six points thanks to an assist. Both cost 4.0m.
One busy afternoon against Newcastle is not a guarantee for the rest of the season. A single match can easily skew total counts if a team spends 80 minutes defending their own penalty box. But over six gameweeks, underlying rates highlight who routinely gets stuck in.
Season to date rates per 90 minutes. Minimum 60 minutes played.
Looking across the season to date, Andrey Santos leads all players with 19.76 defensive actions per 90 minutes. However, he has played only 82 minutes across six gameweeks. That is too small a sample to trust him in your starting lineup.
Mainoo is the more realistic option. He has played 444 minutes across five starts, averaging 14.8 defensive actions per 90. He hit 17 actions in gameweek 6 against Tottenham, easily clearing the 12-action bar for midfielders. At 5.5m, he turns dirty work into points even when he fails to score or assist.
MainooLermaSeason to date comparison. Mainoo has 444 minutes; Lerma has 122 minutes.
Lerma posts higher underlying numbers per 90 than Mainoo, averaging 17.7 defensive actions and 0.57 xGI per 90. But Lerma has logged just 122 minutes this season. High rates mean nothing if the player sits on the bench.
If you need a fifth defender before the deadline, look for cheap starters in teams that face heavy pressure. A 4.0m defender like Thomas who plays 90 minutes gives you two routes to points. Clean sheets are hard to predict, but tackling is not.