The surprising Celtics were carried up to the All-Star Break by the scoring leadership of point guard Isaiah Thomas, but over the last seven weeks they’ve ranked among the league leaders at the other end of the floor – a crucial improvement. While they haven’t entirely regained their old defensive scrappiness, they promise to be a more talented postseason team thanks to power forward Al Horford and shooting guard Avery Bradley, the Celtics’ No. 2 scorer and lockdown defender who was sidelined from the playoffs last year.

A big question is whether the Celtics will be able to elevate their play: They sneaked past Cleveland to the No. 1 seed by beating the lesser opponents, which enabled the Celtics to survive their 5-10 record against Nos. 2-5 in the East.

Boston split four games with the underperforming Bulls, who appeared to be preparing for next year when they packaged veterans Taj Gibson and Doug McDermott for second-year point guard Cameron Payne at the trade deadline. In spite of their .500 record and frustrating inconsistency, the Bulls have established star power in Jimmy Butler, Dwyane Wade and Rajon Rondo, the former Celtic who is remembered in Boston for putting up big numbers when the lights were brightest.

3 quick questions and answers

1. Which Celtic will take pressure off Isaiah Thomas? The Bulls’ upset formula was established in the first round last year by the Hawks, who advanced by holding Thomas to 75 points (24 of 72 overall and 6 of 28 from the arc) in their four wins. Chicago will be aiming to rough-up Thomas and double-team the ball out of his hands, forcing other Celtics to make big shots. Thomas has become a better playmaker for his teammates off the dribble, and his ultimate success will depend on the shotmaking of Bradley (16.4 ppg this season), Horford (14.0) and others.

2. Will Wade reprise his 2016 postseason? Last year with Miami, the future Hall-of-Famer elevated his playoff scoring to 21.4 ppg while converting 12 of 23 (52.2%) from the arc after going 7 for 44 during the regular season. It’s asking a lot from 35 year old Wade, who returned from an elbow injury faster than expected in hope of salvaging his debut season in his hometown of Chicago. Wade generated a respectable 18.5 ppg, but the Bulls will need big performances – especially down the stretch – if they want to pressure the young Celtics.

3. Can the Celtics break through? Remember the strain that Toronto overcame to win its opening round in seven tight games last year? The Celtics may feel similar pressure. They haven’t won a playoff series since the Big 3 were together in 2012 and – with only two wins by a dozen points or more over playoff teams this season - they tend to find themselves in a lot of tight fourth quarters. The longterm upside is very high for this young team, but in the city of champions there is great demand for postseason progress from the surprising No. 1 seed. Now.

The number to know

40-9 -- In their two wins over the Celtics this season (both in Chicago), the Bulls outscored the Celtics 40-9 on second chance points. The Celtics ranked 27th in defensive rebounding percentage, and are matched up with the league's fourth best offensive rebounding team. The 15.0 offensive rebounds the Bulls averaged in the four games were their highest average against any Eastern Conference opponent. But in the Celtics' two wins, they were able to keep pace on the glass, with both teams totaling 25 second chance points in Boston. The good news for the Celtics is that the Bulls haven't been as good an offensive rebounding team since trading Taj Gibson (they rank 18th in offensive rebounding percentage at 23.8 percent since the break) as they were before the trade (they ranked at 28.4 percent second prior to the break). If the Celtics can limit the Bulls' second chances, they'll be in good shape.

Making the pick

The Celtics are sure to experience several tense moments and self-doubt, especially against the talented but unfulfilled Bulls – who with two inspired weeks could bring dignity to their otherwise sorry season. But Boston will have many advantages. Its passionate homecourt will be crucial against the Bulls (16-25 on the road this season), and its weakness on the glass isn’t likely to be punished by Chicago, whose rebounding suffered after the departure of Gibson. The unified Celtics hold a huge lead in terms of cameraderie and morale over the scuffling Bulls, and they also have the East’s leading closer in Thomas (9.8 points per fourth quarter). Though he averaged ``only’’ 24.8 ppg against Chicago, Thomas succeeded in shooting 53.8% overall and 48.4% from the 3-point line. Thomas is at his best in the biggest moments, and he can be expected to make wise decisions against the double-teams. Boston in 6.