That's slightly a disservice to Liverpool's new #1, Klopp's third signing since taking over. Only slightly.
Both played 34 league games. Both conceded 42 goals. Loris Karius faced a lot, lot more shots than Simon Mignolet.
Mignolet still somehow gets by on his "shot-shopper" reputation, which is supposed to make up for his shaky command of the penalty box, mediocre-at-best distribution, and propensity for errors.
There aren't may shot-stoppers who average 63.1% save percentage, better than only Rob Elliott, Brad Guzan, and John Ruddy for regular goalkeepers in last season's Premier League. And he wasn't much better the two seasons before, saving 67.4% and 67.5% of shots faced in the Premier League.
Karius saved 74.4% last season, and in fewer games, 75.3% of the shots faced in 2014-15 and 76.2% in 2013-14.
Karius saved higher percentage of shots on-target in total, Danger Zone shots, Wide Box shots, and Outside the Box shots. He saved a higher percentage of Clear Cut Chances, as well as two of the seven penalties he faced (three scored, two missed). In every conceivable "shot-stopping" metric, Karius was better last season, and often by a healthy margin.
Command of the penalty box? Karius made 81 successful claims last season with just one failed claim, as well as 16 punches. Mignolet made 74 successful claims, but failed on nine (by far the most in the league), as well as 17 punches. Karius isn't the most awe-inspiring, just about average for Bundesliga keepers, but average remains better than Liverpool have done in the last few seasons. Especially last season.
Distribution? Mignolet has a higher pass accuracy (60.6% versus 54.1%) but that doesn't quantify a) Mainz's very different playing style or b) how many times I've screamed at the television as Mignolet holds onto the ball for five seconds while the opposition retreats into position before he plays a safe pass which gets Liverpool nowhere.
Defensive errors? Karius made three last season, none leading to a goal. Mignolet made six – joint-most in the league – four of which led to a goal.
1/3 Minutes per error#Karius career every 835 mins— Dan Kennett (@DanKennett) May 24, 2016
All LFC GK since 2011/12, every 563 mins
All EPL GK since 2011/12, every 747 mins
There are disclaimers, because there are always disclaimers. Karius is only 22 (for one more month) – both a good and bad thing – and while he spent a little more than two years in Manchester City's academy (no, he doesn't count as a homegrown player), he's never played in the Premier League. A league where teams play a lot more crosses and defenders get away with a lot more contact.
More notably, and probably painfully, I hesitate to remind that I wrote similar three years ago. "Wow, look at this younger keeper who's saved a bunch of shots, including more shots in dangerous positions, compared to Liverpool's current mistake-prone keeper who faced a lot less shots and has gotten worse in each of the last three seasons." Mignolet's save percentage and error frequency in his last two seasons at Sunderland is almost exactly the same as Karius' last two for Mainz. And then the Simon Mignolet Era happened. So, caveat emptor, etc.
Do we blame Rodgers for Mignolet's decline? The difference in playing, and defending, style? Liverpool's ever-changing, often-disappointing defense? The presence of Martin Skrtel, whether or not he's playing? Unfireable, unkillable, will-be-here-with-the-cockroaches-and-Keith-Richards-after-the-nuclear-armageddon goalkeeping coach John Achterberg?
Yeah, probably those things too. And, hopefully, Liverpool will also upgrade on both defenders and goalkeeping coach this summer. Both are very much needed, and Liverpool have already started with the free transfer signing of Jöel Matip. Goalkeeper is a tough position. Good goalkeepers go through baffling swoons, mediocre goalkeepers all of a sudden play their faces off (often, amazingly, against Liverpool). Predicting how goalkeepers will play, and react to a new side and style, is not easy.
The short version is that Klopp signed his first-choice goalkeeping target, from a club and league he's very familiar with. Liverpool will pay all of £4.7m as a transfer fee, just about half of what Mignolet cost. Karius' wages will almost certainly be no more than Bogdan's, if not lower, as Bogdan signed as a free transfer. Karius has a lot of time to adjust to Liverpool, and the league, at only 22 years old. And it's only May 25.
It's a start to what'll be a very important summer for Liverpool. And it's a damned handsome start.