I’d disagree on this. Timelord is better at just about everything than Allen other than health (that’s obviously a significant issue here, and I’m reading this post to refer to value when playing rather than the value of being able to play and responding accordingly). Timelord rates better by LEBRON and DARKO, and RAPTOR views them as having been fairly even in terms of value when playing. Timelord has a TS% in the low .700s, considerably higher than Allen’s mid-.600s efficiency despite a usage that, last year, was just 1.5% lower—and Timelord has a trend of increasing usage without loss of efficiency. Timelord has a higher rebounding rate, and doubles Allen’s rates of assists, steals, and blocks while only turning over the ball slightly more. Via the eye test, Timelord pops in a way Allen doesn’t. He has defensive versatility to defend down on switches that Allen lacks, he is a major disruptive presence on the defensive end (although still has lapses that detract from his overall value on that end), and his combination of rim running and passing impacted Boston’s offense last year in ways that stretched beyond his individual stats.I like Jarrett Allen and agree there is upside still remaining. Where I struggle with that contract is you are betting on what I'd say is about a 10% or so outcome for him. He's a good defensive center, but not elite. Maybe he takes a step up defensively and becomes a top level help defender, but far from sure thing. He's solid offensively and very efficient, but we haven't seen a lot of reason to think he's a 18-20 point a game guy either and he can't really pass (so, even if he somehow takes a huge step up from what we've seen it isn't going to be transformative as he's really just a finisher). He's already a very good rebounder.
So if you put together improvement in the first two and continued very good rebounding you get to a guy who is a top-5 center, maybe even top 3. That is worth this contract for sure. But it also assumes a bunch of growth across his game, and unless you get that you're overpaying a top-10 center who is not elite at anything (but also not bad at anything).
Allen is a better player overall right now than TL, but I'd rather TL on his deal than Allen on his for sure---you have a chance TL is elite defensively and he is a more versatile offensive player thanks to the passing even if he's vastly less consistent. If you were, say, the Bucks you might prefer Allen's certainty but that isn't really where the Cavs (or Celtics) are....the lack of elite upside is an issue at that salary level
Allen is a good player with a real role in the league. Timelord is a player that, if he can be healthy (a big if) will play in All Star games. The talent isn’t close. The value probably should be, with a lot more health risk in the Timelord contract discounting his significantly higher talent level.