As overall player, he is. I would rank him only above Cash and Krajicek, and can be made cases for both he was better or worst than Stich. But all other OE winners are clearly better player than Ivanisevic.
As Wimbledon/Grass player he used to be good, instead.
But this statements aren't much important in this discussion, I'm arguing 2001 Wimbledon Ivanisevic was one of the weakest OE Wimbledon champions.
He was 3 years removed from his last Wimbledon final. In these 3 years he had 67-72 record(48,2%). His best result in this span was a Master QF in 1998. In slams 4R at 1998 US Open and 1999 Wimbledon.
In 2000 AO-2001 RG his results in slams was: 1x 2R loss, 3x 1R losses, 1x 1Q loss, 1x absent. He was ranked #125 before Wimbledon.
After that tournament never had relevant results going 23-31(42,6%) until his retirement in 2004.
The schedule wasn't so hard too, just watching the opponents names can be misleading. I think a schedule is hard when you have to play a legit finalist/semifinalist before the final/semifinal or some winners/multiple-winners.
This was Ivanisevic schedule:
1R: Jonsson - Nothing to say here.
2R: Moya - Good player, but awful grass player. He hadn't reached the 3R round before that match. And he only do it in 2004(4R). He has an overall 7-8 record at Wimbledon.
3R: Roddick - Big name here, but he was a not even 19 years old Roddick ranked #33, who played for his third time a GS and for the first time Wimbledon.
4R: Rusedeski - This is maybe a trickier fourth round than average. But Rusedeski had only one Wimbledon QF and was long time removed from his best seasons in 1997-98. He was #40. Not much trickier than the average.
QF: Safin - Reaching QF is the second best results ever for Safin at Wimbledon. And only in 2008 he reached the SF. Aside from these two he was eliminated in 1R-3R everytime. Not an easy opponent because he was a very good player in his prime(He was USO reigning champ), but you can have a lot better opponents at this round.
SF: Henman - Consistent Wimbledon player. But never reached a final.
F: Rafter - Two time finalist, but with 0-2 record. Not the hardest opponent you can play in a final.
This schedule would probably be a picnic for 1994-95 Ivanisevic(Who wasn't Borg btw). In 2001 he struggled playing 14 sets in the last three rounds.
Hopefully I explained well why I'm quite sure 2001 Ivanisevic was one of the weakest Wimbledon champions ever. He was terrible for long time before that tournament, and after that until his retirement. He hadn't an elite schedule and struggled to win the tournament.
However, that was an epic run, nothing to say about that.
Yeah, I was trying to not be biased being a Nole fan, and, probably, I overcompensated
.
But I think I penalized Nole more in favor of Federer than Rafa.
Nadal closing around 20 is a logical one in my opinion:
-I can't see anyone beat him at RG aside from his 2009, 2015 and 2016 performances(I gave 2005 at Kuerten, but it's very doubtful). He could be beaten by peak Nole(And maybe Federer) in his first RG runs, but this can't happen in this scenario. There are 11/12 slams(And counting) here.
-His peaks at other slams were really high. Beat prime/peak Federer at Wimbledon in 2008 and Australian Open in 2009 and peak/prime Nole in USO 2013. Can be made a strong case for Nole to be in a 2011 form from late 2010 too, so USO 2010 is quite impressive, altough i have doubts he could beat 2011 Nole. In 2010 Wimbledon he hasn't elite competition and it's difficult to say how much high was his level, this situation is comparable with Federer slams until 2006. I think he has the edges in other 3/4 slams.
-He could had lost 2017/2019 USO vs 2012 Murray/2018 Nole and 2014 Cilic(And 2020 Nole maybe?). But his 2006 and 2007 runs to WIM final, stopped playing a good and an even match vs peak Federer, happens in early 2000s with bad competition(Maybe deep, but with very low peak).
-He was stopped by peak Nole in three consecutive 2011/12 finals where his level was very high. Not sure he couldn't beat 2006/07 Federer in some of those. [Edit: 2017 AO is not a case, I forget 2018 Nole would be there.]
So I count 16 slams at very least(11 RG, counting 2019 and not 2005, Wimbledon 2006-07-08, AO 2009, USO 2013), and it's reasoneable 2020-22 Nadal could be the front runner in 2015-17 RG field.
I'm quite sure 20 at the end of his career is a fair prediction. I would predict 0-2 slams less than his real tally when his career will be over.
It's also worth noting that "everyone born in 1981" is a good combination for Federer, because Rafa and Nole worst years overlap, leaving an open field for Fed in late 2010 and 2011(A bit too early for Murray to be a real concern too),
I was thinking at a scenario swapping Murray and Federer age(So Murray 1981, Nadal 1986, Nole 1987, Federer 1987). And I'm quite sure Federer will finish with the least number of slams between Big 3. With Murray winning a lot more than what he really won and what he could had won in this scenario too.