SAF did pretty well at St Mirren, then of course Aberdeen.
When he took over St Mirren they were languishing in the bottom half of the old 2nd division with crowds of about 1000 (and there were only 2 divisions in those days) ... in his first season, with the help of league reconstruction he took them up to the new D1, then finished in mid-table the next season before winning D1 the year after and steering the Buddies to the Premier .... managed to avoid relegation in his first season in the Premier but was sacked for breaking club rules (allegedly). that's a pretty good record at a club that is not exactly rolling in cash
Moved to Aberdeen in 1978 and completed 8 full seasons with the Dons, winning trophies in 6 of them. He may have had more resources than some teams, but it should be noted that prior to Ferguson arriving, even with those extra resources, Aberdeen last won the league in 1955, the SFA Cup in 1970, and the League Cup in 1976
ST MIRREN
1974/75: Finishes 6th in D2. League rearrangement sees them up to new D1. SFA Cup Rd 2, League Cup - R1 group stage
1975/76: 6th in D1. SFA Cup Rd 3, League Cup - R1 group stage
1976/77: Wins First Division, SFA Cup 4th Rd, League Cup - R1 group stage
1977/78: Finished 8th in Premier Division, SFA Cup 3rd Rd, League Cup QF. Sacked
ABERDEEN
1978/79: Finishes 4th in Premier Division, SFA Cup SF, League Cup runners-up
1979/80: Wins Premier Division (1pt ahead of Celtic), SFA Cup SF, League Cup runners-up
1980/81: 2nd in Premier Division (7pts behind Celtic), SFA Cup 4th Rd, League Cup QF
1981/82: 2nd in Premier Division (2pts behind Celtic), Wins SFA Cup, League Cup SF
1982/83: 3rd in Premier Division (1pt behind DUFC, level with Celtic), Wins SFA Cup, League Cup QF, Wins Cup Winners Cup, Wins UEFA Super Cup
1983:84: Wins Premier Division, (7pts ahead of Celtic), Wins SFA Cup, League Cup SF, Cup Winners Cup SF
1984/85: Wins Premier Division, (7pts ahead of Celtic), SFA Cup SF, League Cup Rd2
1985/86: 4th in Premier Division (6pts behind Celtic), Wins SFA Cup, Wins League Cup
1986/87: 4th in Premier division (11pts behind Rangers), SFA Cup 3rd Rd, League Cup QF. Leaves in Nov 1986 for Man Utd
I have no feelings toward Aberdeen or Man Utd, and kinda dislike St Mirren but regardless of that, I dont think you can view Ferguson as anything other than a managerial legend .... whoever replaces him is on a hiding to nothing .... look at the managerial record after Matt Busby - the next few didnt last long, until Tommy Doc, then Sexton and Atkinson came along for about 5 years each but with Ferguson having done 27 years (3 more than Busby) .... how patient will they be with the new guy ?