Allen had a career WAR of 58.7, 126th among position players. He had three top 5 finishes, including a 1st. But none back to back. His 4 best were 8.8-8.6-7.5-6.4. Three of those were consecutive (but not the 8.6). His best three consecutive seasons add up to 22.7.
Boyer had a career WAR of 62.8, 104th among position players. He had four top 5 finishes, including a three years in a row. But never a first place finish (3rd was his best). His 4 best were 7.9-7.4-6.8-6.4. Those all came in 154 game seasons, which is about 5% shorter than the 162 game seasons Allen's best years came in. His best three consecutive seasons add up to 22.1 (if we increased that by 5% it would be 23.2).
Boyer has the edge in career WAR. Allen has the edge in best three consecutive season, although only Boyer had three straight in the top 5.
Allen is hurt by fielding with a -16.5 defensive WAR. Boyer has a +10.6 defensive WAR.
I usually think that significant career value and significant peak value should be enough for the Hall. Three straight top 5 finishes in WAR seems pretty good for Boyer along with being 104th among position players.
But Allen's best three consecutive seasons add up to 22.7 or almost 7.6 per year. Sean Forman says that a WAR of 8.0 is MVP caliber. So he was pretty close to that, on average, for three straight years.
If it were just based on hitting, Allen had two 1st place finishes and four other top 5 finishes in offensive WAR. His career rank is 60th. Very impressive.
He missed 44 games in 1968 and 40 in 1969 while hitting 33 and 32 HRs in those years, respectively. A full season might have meant over 40 HRs in each year. Maybe something like that might have cemented an image of him as a top slugger. He also played only 148 games in 1972 while hitting 37.
Allen also had three 1st place finishes in OPS+ and four other top 5 finishes. He led the NL in both 1966-67 when Aaron, Mays, McCovey and Billy Williams were all still good or near their primes. Allen was also 2nd in 1968.
Both Allen and Boyer seem to have enough career value and enough peak value to be in the Hall.